Damian Ramon General appeals his convictions for failure to remain at the scene of an accident in violation of Maryland *479Code (1957, 1999 Repl.Vol., 2001 Supp.) § 20-102(a) of the Transportation Article,1 failure to return to the scene of an accident in violation of § 20-102(b), failure to render reasonable assistance in violation of § 20-104(a), and negligent driving in violation of § 21-901.1(b). The single question that he raises is whether the trial court erred in refusing to instruct the jury concerning mistake of fact as a defense. We shall answer that question in the affirmative, reverse the Court of Special Appeals, and remand the case for a new trial.
In the early morning hours of December, 11, 1997, the police recovered the body of Lynn Thompson from the shoulder of southbound 1-95, the Capital Beltway, in Prince George’s County. Damian Ramon General, petitioner, had been driving the car that struck and killed Ms. Thompson, and he did not stop after he struck her. The next morning, petitioner gave a statement to the police, which the State introduced as evidence in its case-in-chief at trial. He told them the following:
“I was dropping my brother off at the ahm, at a hotel. I was going south, going to my Mother’s house____ [S]he lives off St. Barnabas Road. Ahm and it, it will be a bag, something white was in the, in the far right hand lane and it was a three or a sixteen wheeler beside me on my left. Imagine as I got closer to it, I realized it probably was something, something big, so I tried to move over to my right, so when I moved over, I mean my left. I moved over to my left and I thought I had missed it; that’s when I heard that it hit the side of the, the light. By it being dark I went off, I got off at St. Barnabas, Marlow Heights exit, I went and stopped at the gas station to look at the car and the yellow blinker light was gone, so then I went on home and told my mother. Told my mother that I wrecked Troy’s car, I know he’s going to get me for that, and then she told me don’t worry about it, we’ll see about it in the morning. I got up the next morning and looked at it again, *480I didn’t see no, I didn’t see nothing else but the light gone, the side fender was bent.”
Trooper First Class David Reinholt of the Maryland State Police testified at trial as an expert in the field of accident reconstruction. In his opinion, the impact of petitioner’s car striking Ms. Thompson occurred on the right shoulder of the roadway, and petitioner’s statement was not consistent with the physical evidence.2
Defense counsel requested the Maryland State Bar Association, Inc., Criminal Pattern Jury Instruction (MPJICr) 5:06, which addresses the mistake of fact defense.3 The trial court denied the request, stating that such an instruction was not applicable under the factual scenario of the case.4 *481The court did, however, instruct the jury as to the requisite intent and knowledge of the defendant.
The trial court instructed the jury as to proof of intent in accord with MCJI-Cr 3:31. The court told the jury as follows:
“I instruct you that intent is a state of mind and ordinarily cannot be proven directly, because there is no way of looking into another person’s mind. Therefore a defendant’s intent may be shown by surrounding circumstances. In determining the defendant’s intent, you may consider the defendant’s acts and statements, as well as the surrounding circumstances. Further, you may but are not required to infer that a person ordinarily intends the natural and probable consequences of his acts.”
The trial court instructed the jury as to the requisite knowledge of the defendant as follows:
“Ladies and Gentlemen, the charges of failing to remain at the scene of an accident involving bodily injury or death, failing to return to the scene of an accident involving personal injury or death, and failing to render assistance to a person injured in an accident require the State to prove beyond a reasonable doubt that the defendant had knowledge of both the accident and the underlying injury in order *482for the defendant to be found guilty of each of the three charges.... Knowledge in the context of this case can be proven in one of two ways. The first way is actual knowledge. In other words did the State produce any evidence that the defendant actually saw or perceived the accident or injury? The second way in which knowledge is proven is by showing that the defendant should have known that an accident occurred or should have anticipated that ... the accident resulted in an injury to a person. The term should have known is an objective standard and not a subjective one. It means that given all the evidence that you believe you are to determine whether a reasonable person who possessed all of the information at the time of the collision should have known that a collision occurred and should have anticipated that an accident resulted in an injury to a person.”
Although the court refused to give the requested mistake of fact instruction, the court granted defense counsel’s request to argue mistake of fact in closing argument.
Petitioner was convicted of all charges. He noted a timely appeal to the Court of Special Appeals. In an unreported opinion, that court affirmed the judgments. The court reasoned that “[i]f the jury is adequately instructed as to the intent required for conviction, the mistake of fact instruction is superfluous.” The court then determined that the critical inquiry is whether the instructions as given adequately defined the intent necessary to convict petitioner. Following an examination of the intent instruction, the intermediate appellate court concluded:
“The trial court’s charge instructed the jury to convict appellant only if it found beyond a reasonable doubt that the defendant knew or should have known that an accident occurred. Because the elements of the offense set forth in the trial court’s charge forced the jury to consider appellant’s alleged mistake of fact before conviction, the omission of a mistake of fact instruction did not cause appellant any actual harm.”
*483The court held that the trial court’s instructions “fairly covered” the mistake of fact instruction requested by petitioner, and, thus, no error occurred in the failure to give the instruction requested by petitioner. We granted certiorari to consider the following question:
“Does a jury instruction on the requisite intent necessary to support a conviction on the charged offenses relieve the trial court of the obligation to instruct the jury on a ‘mistake of fact’ defense generated by the facts, and, specifically, was it error for the trial court in this case to fail to give the jury an instruction on ‘mistake of fact’ generated in this case?”
Petitioner argues that he acted under a mistake of fact, and, as such, he is not criminally responsible for his act. He argues that he is not guilty of the charges because, at the time that his automobile struck Ms. Thompson, he actually and reasonably believed that he struck a trash bag and not a person. The trial court gave a proof of intent instruction, but refused to give defense counsel’s requested instruction on mistake of fact. The State argues that the trial court’s instruction on the mental state required for conviction of the offenses charged adequately covered the mistake of fact defense.
As a general rule, mistake of fact is a recognized common law defense to certain crimes.5 See, e.g., Outmez-*484guine v. State, 335 Md. 20, 641 A.2d 870 (1994) (quoting Garnett v. State, 332 Md. 571, 632 A.2d 797 (1993)) (Bell, J., dissenting) (stating that, when a defendant generates the issue of mistake of fact, the State must prove beyond a reasonable doubt that the act was committed without any mistake of fact); Clark & Marshall Crimes, 323 (Marian Barnes ed., 7th ed.1967) (stating that ignorance or nonnegligent mistake of fact as a defense was well settled at common law). Mistake or ignorance of fact exists when the actor does not know what the actual facts are or believes them to be other than as they are. In essence, a mistake of fact is a defense when it negates the existence of the mental state essential to the crime charged. See Wayne R. LaFave & Austin W. Scott, Jr., Substantive Criminal Law § 5.1 (2d ed.1986).6
The issue posed by our grant of certiorari is whether a jury instruction on the requisite intent necessary to support a conviction on the charged offenses relieves the trial court of *485the obligation to instruct the jury on a mistake of fact defense generated by the evidence. We answer that question in the negative.
Generally, it is the duty of the trial judge to instruct the jury as to the applicable law of the case. See Maryland Rule 4-325; Roach v. State, 358 Md. 418, 749 A.2d 787 (2000). Rule 4-325 provides, in pertinent part:
“The court may, and at the request of any party shall, instruct the jury as to the applicable law and the extent to which the instructions are binding. The court may give its instructions orally or, with the consent of the parties, in writing instead of orally. The court need not grant a requested instruction if the matter is fairly covered by instructions actually given.”
Maryland Rule 4-325(c). Thus, it is clear that the trial judge is required to give a requested instruction that correctly states the applicable law and that has not been fairly covered in other instructions.
We have often said that the main purpose of jury instructions is to aid the jury in clearly understanding the case, to provide guidance for the jury’s deliberations, and to help the jury arrive at a correct verdict. See Chambers v. State, 337 Md. 44, 650 A.2d 727 (1994). Jury instructions direct the jury’s attention to the legal principles that apply to the facts of the case. See Robertson v. State, 112 Md.App. 366, 685 A.2d 805 (1996).
The defendant is entitled to have the jury instructed on any theory of the defense that is fairly supported by the evidence. See Sims v. State, 319 Md. 540, 573 A.2d 1317 (1990); Goddard v. United States, 557 A.2d 1315 (D.C.1989); 4 Wharton’s Criminal Procedure § 538 (Charles E. Torcia ed., 12th ed.1976) (stating that the accused has a right to have the jury instructed on the theory of the defense). Once the defendant properly has generated the defense of mistake of fact, he or she is entitled to have the jury understand that the State must still prove each element of the crime beyond a reasonable doubt and that the burden never shifts to the *486defendant. The trial judge must convey to the jury that its “determination that the affirmative defense has not been established is essential to finding that the [State] has met its burden.” Commonwealth v. Cottam, 420 Pa.Super. 311, 616 A.2d 988, 1000-01 (1992).7 As in an alibi defense, “such an instruction is necessary due to the danger that the failure to prove the defense will be taken by the jury as a sign of the defendant’s guilt.” Commonwealth v. Pounds, 490 Pa. 621, 633-34, 417 A.2d 597 (1980).
As Chief Justice Rehnquist stated in Mathews v. United States, 485 U.S. 58, 63, 108 S.Ct. 883, 887, 99 L.Ed.2d 54 (1988) (citations omitted): “As a general proposition a defendant is entitled to an instruction as to any recognized defense for which there exists evidence sufficient for a reasonable jury to find in his favor. A parallel rule has been applied in the context of a lesser included offense instruction____”
The rationale supporting a defendant’s right to an alibi instruction is equally applicable to a defendant’s right to an instruction on mistake of fact. In Smith v. State, 302 Md. 175, 486 A.2d 196 (1985), this Court was confronted with the issue of whether a defendant is entitled to a specific instruction on alibi. We held that the trial court committed reversible error in refusing to instruct the jury on alibi, reasoning that, when the evidence in a criminal case has generated the issue of alibi, and when the defendant has requested an instruction addressed to the matter of alibi, the defendant is entitled to a specific alibi instruction, and the trial court’s general instructions concerning the prosecution’s burden of proof, etc., are not deemed fairly to cover the matter of alibi. See id. at 180, 486 A.2d at 198.
Whether a particular instruction must be given depends upon whether there is any evidence in the case that *487supports the instruction; it the requested instruction has not been generated by the evidence, the trial court is not required to give it. See Roach, 358 Md. at 428-29, 749 A.2d at 792-93; Hof v. State, 337 Md. 581, 655 A.2d 370 (1995); Binnie v. State, 321 Md. 572, 582, 583 A.2d 1037, 1041 (1991). Whether the evidence is sufficient to generate the requested instruction in the first instance is a question of law for the judge.8 See Roach, 358 Md. at 428, 749 A.2d at 792; Dykes v. State, 319 Md. 206, 221, 571 A.2d 1251, 1259 (1990). In evaluating whether competent evidence exists to generate the requested instruction, we view the evidence in the light most favorable to the accused. See Stagner v. State, 842 P.2d 520, 522 (Wyo. 1992).
In reviewing the adequacy of jury instructions, we review the instructions as a whole. If the instructions given as a whole adequately cover the theory of the defense, the trial court does not need to give the specific requested instruction. See Roach, 358 Md. at 427, 749 A.2d at 792; Mack v. State, 300 Md. 583, 592, 479 A.2d 1344, 1348 (1984). We emphasize, however, that, although we hold that a defendant is entitled to a theory of the defense instruction, a defendant is not entitled to a mirror-image instruction in other settings. A skilled advocate could take nearly any of the instructions typically given by a court and, with some imagination, create a *488negative mirror image of it. The principle articulated in Maryland Rule 4-325(c) still governs: “[t]he court need not grant a requested instruction if the matter is fairly covered by instructions actually given.”
In the instant case, petitioner’s primary defense at trial was that he did not know that his vehicle had hit a person. The evidence before the jury was that, at night, petitioner, traveling in the far right travel lane, struck an object lying on the roadway in the right portion of his lane of travel. The object appeared to him to be “a bag, something white.” The morning after the incident, petitioner went to the police station and gave a statement to the police, offering his version of the event and admitting that he was driving the vehicle that apparently struck and killed Ms. Thompson. Petitioner did not testify at trial, but the State offered his pretrial statement into evidence.
As we have noted, knowledge that the defendant struck a person is an element of the charged offenses of §§ 20-102(a) and (b) and 20-104(a). If petitioner did not know that he struck a person and reasonably believed that he merely struck a white bag, then his mistake of fact was a defense to those crimes.9
*489Most other jurisdictions require a mistake of fact instruction even when the trial court instructs the jury as to the required mental element of the charged offense. For example, in People v. Crane, 145 Ill.2d 520, 165 Ill.Dec. 703, 585 N.E.2d 99 (1991), the trial court instructed the jury on self-defense, but refused to instruct the jury on mistake of fact. The Illinois Supreme Court reversed, stating as follows:
“The instruction, while significantly informing the jury of the mental state requirement, does not expressly draw to the jury’s attention the concept of mistake of fact. Since Illinois recognizes the defense of mistake of fact, when this defense is supported by the evidence it is not sufficient to merely inform the jury of the mental state requirements, but it must also be informed of the validity of the mistake of fact defense.”
Id. at 102.
Similarly, the Iowa Supreme Court rejected the State’s argument that an intent instruction adequately covered a properly generated mistake of fact defense. In Iowa, mistake or ignorance of fact is a defense to a crime requiring intent if it was reasonable and not due to carelessness or negligence. See State v. Freeman, 267 N.W.2d 69, 70 (Iowa 1978). In the context of a theft case, the court said:
“We cannot agree the theory of mistake of fact was adequately explained to the jury by the uniform instruction on intent. It is true a mistake of fact would, under its definition, make it impossible for defendant to form a criminal intent.
Mistake of fact nevertheless remains a separate and distinct issue notwithstanding its relation to the State’s duty to prove a criminal intent. Mistake of fact was defendant’s sole and only theory of defense. It did not vanish merely because it can be stated the mistake could not coexist with a criminal intent. We have said: ‘Courts have the duty to *490instruct juries "... on the law applicable to the facts as disclosed by the evidence, and must so instruct if there is evidence admitted which supports some involved issue.” ’ ”
Id. at 71. See Adcock v. State, 260 Ga. 302, 392 S.E.2d 886 (1990) (holding that reversible error can occur from failure to give a mistake of fact instruction even if it is not the defendant’s sole defense); Crane, 165 Ill.Dec. 703, 585 N.E.2d at 102 (holding that “a defendant is entitled to instruction on his theory of the case if there is some foundation for the instruction in the evidence”); Jewell v. Commonwealth, 549 S.W.2d 807, 812 (Ky.1977) (noting that the defense of mistake of fact, when raised, requires an instruction calling it to the jury’s attention); State v. Collin, 741 A.2d 1074 (Me.1999) (holding that, when a defendant raises an affirmative defense supported by competent evidence, the trial court must instruct the jury that the State needs to disprove the affirmative defense in order to convict); Bang v. State, 815 S.W.2d 838, 842 (Tex.App.1991) (holding that “[w]hen an accused creates an issue of mistaken belief as to the culpable mental element of the offense, he is entitled to a defensive instruction on ‘mistake of fact’ ”); Stagner, 842 P.2d at 522 (holding that the theory of the case instruction, where appropriate evidence exists, is a basic tenant of criminal law and a procedural concomitant of due process).
The knowledge and intent instructions, while sufficiently informing the jury of the required mental element, did not expressly direct the jury’s attention to the defense of mistake of fact. Were we to accept the State’s argument that the instruction on intent and knowledge fairly covered the mistake of fact defense, there would never be an occasion to give the instruction. Petitioner was entitled to an instruction on the theory of his defense, as he requested. The trial court abused its discretion in declining to give the requested instruction, and a new trial is in order.10
*491 JUDGMENT OF THE COURT OF SPECIAL APPEALS REVERSED. CASE REMANDED TO THAT COURT WITH INSTRUCTIONS TO REVERSE THE JUDGMENTS OF CONVICTION IN THE CIRCUIT COURT FOR PRINCE GEORGE’S COUNTY AND TO REMAND THIS CASE TO THE CIRCUIT COURT FOR A NEW TRIAL. COSTS IN THIS COURT AND THE COURT OF SPECIAL APPEALS TO BE PAID BY PRINCE GEORGE’S COUNTY.
. Unless otherwise indicated, all statutory references are to Maryland Code (1957, 1999 Repl.Vol., 2001 Supp.), Transportation Article.
. At trial, petitioner called the State Medical Examiner, who testified that, based on the angle of the primary impact to Ms. Thompson’s head and the placement of the paint chip in her head, she had to have been extremely low and facing the vehicle when she was struck.
. MPJI-Cr. 5:06 reads:
"You have heard evidence that the defendant's actions were based on mistake of fact. Mistake of fact is a defense and you are required to find the defendant not guilty if all of the following three factors are present:
(1) the defendant actually believed [alleged mistake];
(2) the defendant's belief and actions were reasonable under the circumstances; and
(3) the defendant did not intend to commit the crime of [crime] and the defendant’s conduct would not have amounted to the crime of [crime] if the mistaken belief had been correct, meaning that, if the true facts were what the defendant thought them to be, the [defendant's conduct would not have been criminal] [defendant would have the defense of (defense) ].
In order to convict the defendant, the State must show that the mistake of fact defense does not apply in this case by proving, beyond a reasonable doubt, that at least one of the three factors previously stated was absent.”
. Before this Court, neither party argues that the defense of mistake of fact was not generated or that it was not applicable to the case. The certiorari petition assumes that the defense was generated and applicable, and neither party disputes that fact. Nor has any party challenged the propriety of the intent instruction as given in this case. The parties’ sole argument is whether a proper and full intent instruction relieves the court of the obligation to instruct on the defense of mistake of fact.
*481We point out, however, that petitioner was charged, inter alia, with violation of Maryland Code (1957, 1999 Repl.Vol., 2001 Supp.) § 20-102 of the Transportation Article (requiring a driver to remain at the scene of an accident resulting in bodily injury or death) and § 20-104 (establishing the duty to give information and render aid). Inasmuch as the defense of mistake of fact goes to the mental state or mens rea of the offense charged, we look at the statute to determine the requisite mental elements.
Sections 20-102 and 20-104 require knowledge that the accident resulted in injury or death to a person, or property damage, respectively. See Comstock v. State, 82 Md.App. 744, 573 A.2d 117 (1990) (holding that, in order for a driver to be convicted of leaving the scene of a personal injury accident, the conditions must have been such that the driver knew, should have known, or reasonably should have anticipated that the accident and the resulting injury occurred). While the word "accident” is not defined specifically in the statute, when used in these sections, it relates solely to occurrences actually resulting in death, personal injury, or property damage. See State Farm Mut. Auto. Ins. Co. v. West, 149 F.Supp. 289 (D.Md.1957).
. In Garnett v. State, 332 Md. 571, 632 A.2d 797 (1993), the Court discussed mistake of fact in the context of statutory rape. Chief Judge Murphy, writing for the Court, addressed the general requirement of the concurrence of mens rea and actus reas for criminal culpability. The Chief Judge noted:
"At common law, a crime occurred only upon the concurrence of an individual’s act and his guilty state of mind. In this regard, it is well understood that generally there are two components of every crime, the actus reus or guilty act and the mens rea or the guilty mind or mental state accompanying a forbidden act. The requirement that an accused have acted with a culpable mental state is an axiom of criminal jurisprudence. Writing for the United States Supreme Court, Justice Robert Jackson observed:
‘The contention that an injury can amount to a crime only when inflicted by intention is no provincial or transient notion. It is as universal and persistent in mature systems of law as belief in *484freedom of the human will and a consequent ability and duty of the normal individual to choose between good and evil.
'Crime as a compound concept, generally constituted only from a concurrence of an evilmeaning mind with an evildoing hand, was congenial to an intense individualism and took deep and early root in American soil.’ Morissette v. United States, 342 U.S. 246, 250-252, 72 S.Ct. 240, 243-244, 96 L.Ed. 288 (1952).’ ”
Id. at 577-78, 632 A.2d at 800.
. A mistake of fact has been described not as a true defense, but instead, like alibi, as a means of showing that the prosecution has not proven beyond a reasonable doubt the essential elements of the crime. See Commonwealth v. Lopez, 433 Mass. 722, 745 N.E.2d 961 (2001); State v. Sexton, 160 NJ. 93, 733 A.2d 1125, 1128 (1999); Model Penal Code § 2.04 (explanatory note recognizing that mistake of fact is a defense to the extent that it negates the mental culpability of the proscribed offense); Wayne R. LaFave & Austin W. Scott, Jr., Substantive Criminal Law, § 5.1 (2d ed.1986) (stating that "[i]nstead of speaking of ignorance or mistake of fact ... as a defense, it would be just as easy to note simply that the defendant cannot be convicted when it is shown that he does not have the mental state required by law for commission of that particular offense”); see generally Dannye Holley, The Influence of the Model Penal Code's Culpability Provisions on State Legislatures: A Study of Lost Opportunities, Including Abolishing the Mistake of Fact Doctrine, 27 Sw. U.L.Rev. 229, 230 (1997).
. Even though the Pennsylvania court used the term “affirmative defense,” the burden of persuasion remains on the State to prove the offense beyond a reasonable doubt, and that burden does not shift to the defendant.
. In Dykes v. State, 319 Md. 206, 571 A.2d 1251 (1990), we discussed the level of evidence necessary to generate an instruction. We did so in the context of the trial court's refusal to give an instruction on imperfect self-defense. We noted:
“Some evidence is not strictured by the test of a specific standard. It calls for no more than what it says — 'some,' as that word is understood in common, everyday usage. It need not rise to the level of ‘beyond reasonable doubt' or ‘clear and convincing' or ‘preponderance.’ The source of the evidence is immaterial; it may emanate solely from the defendant. It is of no matter that the self-defense claim is overwhelmed by evidence to the contrary. If there is any evidence relied on by the defendant which, if believed, would support his claim that he acted in self-defense, the defendant has met his burden. Then the baton is passed to the State. It must shoulder the burden of proving beyond a reasonable doubt to the satisfaction of the jury that the defendant did not kill in self-defense."
Id. at 216-17, 571 A.2d at 1257.
. Some courts have held that mistake of fact is not a defense if the defendant’s erroneous belief was due to his or her own negligence or willful blindness. See Model Penal Code § 2.04. The question of when ignorance or mistake of fact will afford a defense to a criminal charge has not been briefed or argued in this case. Neither has the State argued that mistake of fact is not a defense to the negligent driving charge. Consequently, we shall not address it.
We note, however, that, in this case, the State has not argued that petitioner was negligent in not knowing that he struck a person or in not stopping and satisfying the requirements of Maryland Code (1957, 1999 Repl.Vol., 2001 Supp.) § 20-105 of the Transportation Article (creating three separate duties for motorists who damage unattended property: (1) the duty to stop at the scene; (2) the duty to attempt to locate the owner of the unattended property; and (3) if unable to do so, the duty to leave a written notice on the property for the owner). In closing, the State argued that '‘[a]s for the negligent driving, he was driving on the shoulder. We all know it. He was driving on the shoulder in a way that would have or could jeopardize someone's life."
*489Defense counsel argued that ‘‘[h]e was not negligent. He did not run from the scene.”
. If the defendant’s conviction rests upon a charge for which mistake of fact was a defense, and the defense was properly generated, failure to *491instruct the jury on the defense is not harmless error. See People v. Crane. 145 Ill.2d 520, 165 Ill.Dec. 703, 585 N.E.2d 99 (1991); State v. Freeman, 267 N.W.2d 69 (Iowa 1978); Cheser v. State., 904 S.W.2d 239 (Ky.Ct.App. 1994).