(on reassignment).
This case involves a suit brought by McGillivray for false imprisonment. She alleged that defendants Siedschlaw and Larson, acting in consort, caused her unlawful arrest and imprisonment for possession of a controlled substance.1 Specifically, McGillivray alleged that Officer Siedsch-law, a state highway patrolman, arrested her on a drug possession charge without a warrant and without probable cause. McGillivray further alleged that Larson aided and abetted the false imprisonment by instigating the unlawful arrest. The matter was tried before a jury which rendered a verdict in favor of Siedschlaw and against Larson in the amount of $5,000 general damages. The trial court did not grant McGillivray’s motion for a directed verdict against Siedschlaw, her motion for judgment notwithstanding the verdict, or her alternative motion for a new trial. The trial court did, however, grant Larson’s motion for judgment notwithstanding the verdict. Accordingly, the trial court entered a judgment dismissing Siedschlaw and a judgment setting aside the jury verdict against Larson and dismissing the action against Larson. McGillivray appeals from both judgments. We reverse and remand.
McGillivray first contends that the trial court erred in not granting her motion for directed verdict against Siedschlaw because the arrest was made without probable cause and was illegal as a matter of law. Regarding Siedschlaw’s liability for false imprisonment, the issue is whether his arrest of McGillivray was lawful. It is undisputed that the arrest in question was made without a warrant. Without a warrant, the arrest could be valid only if a felony had in fact been committed and Siedschlaw had reasonable cause for believing that McGillivray committed the felony. SDCL 23-22-7(3). This requirement of reasonable cause has been held to be equated with the Fourth Amendment’s requirement of probable cause as follows:
“Probable cause exists where the facts and circumstances within the officers’ knowledge, and of which they have reasonably trustworthy information, are sufficient in themselves to warrant a belief *798by a man of reasonable caution that a crime has been or is being committed.” Klingler v. United States, 1969, 8 Cir., 409 F.2d 299, 303.
See also, State v. Klingler, 1969, 84 S.D. 466, 469-470, 173 N.W.2d 275, 278. It is clear that reasonable cause and probable cause must be measured against an objective standard. Terry v. Ohio, 1968, 392 U.S. 1, 88 S.Ct. 1868, 20 L.Ed.2d 889. Mere good faith on the part of the arresting officer is not enough. Beck v. Ohio, 1964, 379 U.S. 89, 85 S.Ct. 223, 13 L.Ed.2d 142. Further, “when a search is based upon a magistrate’s, rather than a police officer’s, determination of probable cause, the reviewing courts will accept evidence of a less ‘judicially competent or persuasive character than would have justified an officer in acting on his own without a warrant’ * *.” Aguilar v. Texas, 1964, 378 U.S. 108, 111, 84 S.Ct. 1509, 1512, 12 L.Ed.2d 723, 726. Thus, when an officer acts on his own and without a warrant, the reviewing courts will require evidence of a more judicially competent or persuasive character.
With this standard in mind, we must review the facts that Siedschlaw had before him. The record reveals that Siedschlaw was given a brown pill by Larson, a cafe waitress whom he had not known previously. Larson indicated to him that she had found the pill on the rug in her apartment and that she thought her roommate was on drugs. Siedschlaw gave the pill to another officer who conducted a field chemical test. The test resulted in a positive reaction for an amphetamine substance. Both Siedsch-law and the testing officer knew that this was not conclusive without a laboratory test. In fact, it wag a part of normal operating procedure to check with the State Chemical Laboratory in Vermillion for confirmation of the presence of an amphetamine substance. Siedschlaw, however, did not submit the pill to the state laboratory for such confirmation in compliance with accepted procedure. Siedschlaw did not know the roommate’s name until moments before the arrest, and he did not know whether the pill which was tested did in fact belong to the roommate. About eight days passed between Siedschlaw’s receipt of the pill and the arrest. In that period of time, he did not attempt to verify the information given to him, such as the roommate’s name, description, activities, or the pill’s true chemical content. We must conclude that on the basis of the meager facts before Siedschlaw he could not determine that a felony had in fact been committed and that the roommate committed the felony.
With regard to informant Larson’s credibility, we have pointed out that the test to determine the sufficiency of an informant’s tip as it relates to probable cause, as set out in Aguilar v. Texas, supra, has been used in determining if probable cause exists where there is an arrest without a warrant. State v. Rigsbee, 1975, S.D., 233 N.W.2d 312, citing McCray v. Illinois, 1967, 386 U.S. 300, 87 S.Ct. 1056, 18 L.Ed.2d 62, and Beck v. Ohio, supra. It is suggested that Larson’s information is inherently reliable because she was a supposedly concerned citizen, as distinguished from a paid police informer. We recognize that less rigid tests of credibility should be applied under such circumstances. State v. Gerber, 1976, S.D., 241 N.W.2d 720. In Gerber, however, we recognized that credibility and reliability were demonstrated because the information furnished in several long-distance phone calls from concerned citizens was fully corroborated by officers prior to issuance of a search warrant. In turn, credibility and reliability were not demonstrated in the present case because the officer did nothing in a period of eight days to investigate or corroborate the meager information he had. Also in Gerber, probable cause was demonstrated to a neutral and detached magistrate prior to the issuance of a search warrant. In the present situation, this protection was not afforded to McGillivray in that Siedschlaw determined probable cause independently and went into her apartment upon Larson’s consent and without a search warrant or an arrest warrant. After reading the record, we do not believe that Siedschlaw had “reasonably trustworthy information” or that a “man of reasonable caution” could conclude that a crime had been committed. Therefore, the requirement of probable cause was not satisfied and the arrest was unlawful.
*799In addition to the conclusion that the arrest was invalid, we are disturbed by the officer’s conduct subsequent to the arrest. After McGillivray informed the officer that the pills were vitamins, those who accompanied Siedschlaw during the arrest expressed their concern that something did not seem right and that McGillivray did not seem to be on drugs. The state’s attorney also suggested to Siedschlaw that McGillivray should be released on her own recognizance. Siedschlaw replied that she had already been booked and that she was going to stay in jail. The day after the arrest, McGilliv-ray’s mother showed Siedschlaw similar pills that belonged to her which were nothing more than vitamin pills. Siedschlaw responded that McGillivray was definitely high on drugs when she was arrested. Additionally, Larson and the other girls who lived with McGillivray went to Siedschlaw’s home. They admitted that they had made a mistake in accusing McGillivray and stated that she was not on drugs and had never used them. Siedschlaw stated that he had a picture of McGillivray at a drug party and insisted to the girls that the pills were indeed drugs. Siedschlaw had no basis in fact for his statements that McGillivray “was definitely high on drugs” when she was arrested, or that he “had a picture of McGillivray at a drug party,” or that the “pills were indeed drugs.” True, these statements were made subsequent to the arrest, but they emphasize the failure of Siedschlaw to make even a cursory investigation of McGillivray prior to arrest, his disregard for the concept of probable cause, and his lack of objectivity in making the arrest. In fact, his completely inaccurate and defensive statements at this juncture lend credence to the claim that Siedschlaw knew the arrest and continuing imprisonment of McGillivray were improper and illegal.
With regard to McGillivray’s motion for directed verdict against Siedschlaw, when the facts before an officer are undisputed, as they are in the present case, the determination as to whether an arrest is legal or illegal is a question of law for the court. Anderson v. Sager, 1949, 8 Cir., 173 F.2d 794; Wilson v. Gutschenritter, 1970, 185 Neb. 311, 175 N.W.2d 282. We hold that on the undisputed facts before Siedschlaw there was insufficient probable cause, and therefore the arrest was illegal as a matter of law and the trial court erred in not granting the motion for directed verdict against the officer.
McGillivray further contends that the trial court erred in granting Larson’s motion for judgment notwithstanding the verdict in that the jury verdict against Larson was supported by the evidence. It is clear that a private citizen who by affirmative action, persuasion, or request assists or abets in an unlawful arrest and detention of another is liable for false imprisonment. Catencamp v. Albright, 1977, S.D., 251 N.W.2d 190; Burkland v. Bliss, 1933, 62 S.D. 91, 252 N.W. 25; Tredway v. Birks, 1932, 59 S.D. 649, 242 N.W. 590; Culver v. Burnside, 1920, 43 S.D. 398, 179 N.W. 490; Huskinson v. Vanderheiden, 1977, 197 Neb. 739, 251 N.W.2d 144; 32 Am.Jur.2d, False Imprisonment, § 34, p. 98. Regarding Larson’s liability for false imprisonment, it appears that the jury was properly instructed as to the circumstances under which a private person may be liable for false arrest and imprisonment for requesting, directing, or instigating an unlawful arrest by a law officer.2 The jury found that Larson was *800indeed liable. The trial court, however, granted judgment notwithstanding the verdict in Larson’s favor, presumably on the fact that if the officer was not liable and the arrest was valid then the private citizen could not be liable either. To reverse the judgment n. o. v., some substantial, credible evidence must be found in the record in support of the verdict. We will view that record in a light most favorable to the jury verdict giving McGillivray the benefit of every available inference. Lytle v. Morgan, 1978, S.D., 270 N.W.2d 359; Meylink v. Minnehaha Co-op. Oil Co., 1938, 66 S.D. 351, 283 N.W. 161.
In examining the record, there is substantial evidence that portrays Larson as suspecting and accusing McGillivray of stealing money from her, finding the pill, getting the other roommates concerned about it, refusing to listen to the landlady, a registered nurse, who suggested she forget about it, giving the pill to Siedschlaw, stating that her roommate was on drugs, directing Siedschlaw to do something about the pill, and meeting with Siedschlaw and the state’s attorney on the afternoon preceding the arrest. In fact, Siedschlaw testified that it was because of this meeting with her that he decided to make the search and the arrest. The question of Larson’s liability went to the jury, and the jury found against her. We hold that the trial court erred in granting the motion for judgment n. o. v. because the jury verdict against Larson was supported by substantial, credible evidence in the record.
The trial court erred in granting Larson’s motion for judgment n. o. v. and in denying the motion for directed verdict against Siedschlaw. The judgments of the trial court are therefore reversed and the matter is remanded to the trial court for a determination of damages against Siedschlaw.
WOLLMAN, C. J., concurs. HENDERSON, J., concurs specially. MORGAN, J., dissents. FOSHEIM, J., deeming himself disqualified, did not participate.. McGillivray was awakened and arrested at approximately 10:30 p. m. on July 21, 1974. She was subsequently booked and fingerprinted, stripped of her clothing and searched, and taken to a Watertown, South Dakota, jail cell containing only a mattress and a stool. McGillivray’s parents were contacted the next morning at 11 a. m. in Madison, South Dakota, and were unable to borrow money from the bank for bail until the following morning. McGillivray was released from the jail on July 23, 1974, in the afternoon. The following week, McGillivray appeared in court, and her case was summarily dismissed because there was no evidence against her.
. Instruction 16 reads as follows:
“Under certain circumstances a private person may be liable for false arrest and imprisonment for requesting, directing or instigating an arrest by a law enforcement officer.
“There is no liability incurred for false arrest if a person merely gives information to an officer tending to show that a crime has been committed or if she acts solely to assist a peace officer in charge of an investigation.
“However, there may be liability for a false arrest where the acts of a person so induce an officer to make an arrest that it can be said that the arrest is not made by the officer of his own volition but made to carry out the request of such person. A person may also be held liable for a false arrest and imprisonment where she gives information that the plaintiff committed a crime when in fact she has no knowledge of such fact or that a crime had been committed.”
Instruction 17 reads in pertinent part as follows:
“The plaintiff has the burden of proving the following issues to be able to recover against the Defendant Larson: *8001. That the Plaintiff was arrested and imprisoned; and
2. That the Defendant Larson instigated the arrest or imprisonment as herein defined;
3. That the arrest was illegal or without probable cause; 4. The extent and duration of Plaintiffs injury and suffering;
5. The amount of her damages.”