Opinion by
Judge RICHMAN.Defendant, James T. Hoffman, appeals the trial court's order denying his motion to suppress evidence seized during the execution of a search warrant. Pursuant to a conditional plea agreement, defendant pleaded guilty to possession with intent to distribute a schedule II controlled substance while preserving the right to appeal the suppression ruling. We vacate the judgment entered on the plea, reverse the trial court's order, and remand the case for further proceedings.
I. Background
Based upon evidence seized during the execution of a search warrant, defendant was charged with one count each of possession with intent to distribute a schedule II controlled substance, possession of a schedule II controlled substance, and child abuse. Defendant was charged as a special offender for having used, displayed, or had available for use a deadly weapon during the commission of the drug offenses.
Before trial, defendant moved to suppress the evidence obtained during the search and as the "fruit" of an unlawful search. Defendant argued that there was no probable cause to support the issuance of the search warrant because it was based on an anonymous informant's tip without sufficient independent corroboration. Following a hearing, the court denied defendant's motion.
Thereafter, defendant and the prosecution entered into a plea agreement whereby defendant agreed to plead guilty to the charge of possession with intent to distribute, with a stipulated six-year sentence to the Department of Corrections, while retaining his right to appeal the court's denial of his motion to suppress. The prosecution agreed to dismiss the remaining counts, including the counts in a separate case. The trial court accepted the plea agreement and sentenced defendant accordingly. This appeal followed.
II. Conditional Guilty Pleas
As a preliminary matter, we address the issue which we requested the parties to address with supplemental briefing: whether conditional guilty pleas are permissible in Colorado and may be reviewed on appeal. Concluding in the affirmative, we then reach the merits of defendant's suppression motion.
The Colorado Supreme Court has not "explicitly endorsed" conditional pleading nor has it explicitly rejected the practice. See People v. McMurtry, 122 P.3d 237, 243 (Colo.2005). In People v. Bachofer, 85 P.3d 615, 617 (Colo.App.2003), a division of this court concluded that a stipulation in a plea agreement preserves the defendant's right to appeal a ruling on a suppression motion, noting that there was no prohibition of conditional pleas in either the statutes or the Colorado Rules of Criminal Procedure and that such pleas are in the interest of judicial economy. After the completion of briefing for this appeal, a different division of this court concluded in People v. Neuhaus, 240 P.3d 391, 394-95 (Colo.App.2009), that in the absence of a statute or rule authorizing conditional plea agreements, they are not permitted under Colorado law.
After considering supplemental briefing on this issue, we agree with the conclusion in Bachofer for the reasons stated there, as well as those set forth below, and decline to follow Neuhaus. See Am. Family Mut. Ins. Co. v. Murakami, 169 P.3d 192, 193 (Colo.App.2007) (one division of the court of appeals is not bound by the decision of another).
Conditional plea agreements can play a significant role in conserving judicial and prosecutorial resources and provide other systemic advantages in criminal cases. As noted in Newhaus, at least thirty-two jurisdictions, including the federal courts and the United States military, have approved of conditional pleas. Six jurisdictions have adopted conditional guilty pleas by judicial decision. The federal courts have accepted conditional pleas pursuant to Fed.R.Crim.P. 1l1(a)(@2) since 1983.
Although Neuhaus describes several reasons why conditional pleas may not be advantageous, most of which are described in the *5advisory committee's notes on the federal rule, we agree with the comment of the advisory committee that the obvious advantages of a conditional plea procedure are not outweighed by any significant or compelling disadvantages. The conditional plea is particularly effective when the issue preserved for appeal is dispositive of the case. See Neuhaus, 240 P.3d at 394-95. Although the prosecution in this case has not conceded that a reversal on appeal of the suppression issue would be dispositive, it has stated in its supplemental brief that "principles of fairness and judicial economy might support consideration of this defendant's suppression issue on appeal."
Accordingly, we conclude that a review of his appeal on the merits is warranted.
III. Motion to Suppress
Defendant argues that the trial court erred when it concluded that (1) probable cause existed to issue the search warrant, and (2) even absent probable cause, the officers acted in good faith in executing the warrant. We agree with defendant.
A. Probable Cause
"Both the United States and Colorado Constitutions prohibit the issuance of a search warrant except upon a showing of probable cause supported by oath or affirmation particularly describing the place to be searched and the things to be seized." People v. Pacheco, 175 P.3d 91, 94 (Colo.2006). "Under the Colorado Constitution, the facts supporting probable cause must be reduced to writing, and so probable cause must be established within the four corners of the warrant or its supporting affidavit." People v. Seott, 227 P.3d 894, 897 (Colo.2010). "Probable cause exists when an affidavit for a search warrant alleges sufficient facts to warrant a person of reasonable caution to believe that contraband or evidence of erimi-nal activity is located at the place to be searched." People v. Miller, 75 P.3d 1108, 1112 (Colo.2003). "To determine whether probable cause exists, we examine the totality of the cireumstances." Id. at 1113; see also Illinois v. Gates, 462 U.S. 213, 103 S.Ct. 2317, 76 L.Ed.2d 527 (1983). "A court reviewing the validity of a search warrant does not engage in de novo review but rather examines whether the magistrate had a substantial basis for concluding that probable cause existed." Pacheco, 175 P.3d at 94.
Because the probable cause standard does not lend itself to mathematical certainties and "[rleasonable minds frequently may differ on the question whether a particular affidavit establishes probable cause," United States v. Leon, 468 U.S. 897, 914, 104 S.Ct. 3405, 82 L.Ed.2d 677 (1984), appellate courts generally defer to the magistrate's determination. People v. Randolph, 4 P.3d 477, 482 (Colo.2000).
Analysis of the totality of the circumstances includes consideration of the informant's veracity or reliability and his or her basis of knowledge. Id. at 481. An informant's reliability may be gauged in part by whether the informant's identity is known and whether he or she previously has provided accurate information to the police. Id. at 482 n. 2. The depth of detail provided by the informant is also relevant in the totality of circumstances analysis, as courts have inferred reliability from an informant's ability to provide details that could not be obtained easily. Id. at 482.
Here, a deputy of the Mesa County Sheriff's Department obtained a warrant to search defendant's trailer by submitting an affidavit presenting (1) information he received from an unidentified informant, (2) the deputy's observations of activity near defendant's trailer on the night before the warrant was issued, but a month after the informant's information was received, (38) an account of two arrests the deputy made after observing the activity near defendant's trailer, and (4) some criminal history related to prior conduct of defendant. Our review of the totality of the cireumstances, including the cumulative effect of the allegations presented in the affidavit, persuades us that there was no substantial basis to conclude that probable cause existed.
1. Unidentified Informant
The deputy's affidavit relates that on February 24, 2007, an informant, "who wants to *6remain anonymous," told the deputy that an older white male with defendant's name drove around in a green Buick sedan and distributed methamphetamine from nightfall until about 2:30 am. The informant stated that defendant lived in a trailer at the west end of the center aisle of a trailer park. The informant stated that defendant had a fake rock with a hollow center in which he commonly kept methamphetamine, sometimes leaving the rock outside of his residence and sometimes bringing it inside. The informant also stated that defendant kept a large amount of cash-profits from drug deals-at his residence, as well as two to three ounces of methamphetamine, which he normally carried in his underwear. The informant described defendant's automobile and identified defendant in a mug shot. The deputy used a computer system to confirm that a person with defendant's name had an address corresponding to the location described by the informant. -
Where, as here, an affidavit is based on an informant's information, the totality of the cireumstances analysis depends on all indicia of reliability, including the informer's veracity and the basis of his or her knowledge, the amount of detail provided, and whether the information was current. Pacheco, 175 P.3d at 94-95. "[An informant's account of criminal activities need not establish the informant's basis of knowledge, so long as the informants statement is sufficiently detailed to allow a judge to reasonably conclude that the informant had access to reliable information about the illegal activities reported to the police." People v. Abeyta, 795 P.2d 1324, 1327 (Colo.1990). However, bare assertions of knowledge are insufficient to establish the basis of an informer's knowledge. Pacheco, 175 P.3d at 95.
But, where an informant's statements do not alone rise to the level of probable cause, it may still be established by independent police corroboration of the information. Id. "Even if an anonymous tip, on its face, does not provide enough detailed information to establish that the informant had access to reliable information, independent police corroboration of some of those details which were provided in the tip nevertheless may support a finding of probable cause." People v. Pate, 878 P.2d 685, 691 (Colo.1994); see also Abeyta, 795 P.2d at 1327 ("[Plolice corroboration of the information that obviously relates to and describes criminal activities may properly be considered in a probable cause determination."). If "an informant is shown to be right about some things, he is probably right about other facts that he has alleged, including the claim that the object of the tip is engaged in criminal activity." Abeyta, 795 P.2d at 1327. However, if only non-criminal activity is corroborated, the question of whether probable cause exists depends on the degree of suspicion that attaches to the particular types of corroborated non-criminal acts and whether the informant provides details that are not easily obtained. Pacheco, 175 P.3d at 95.
"Finally, [the supreme court has] held that doubts must be resolved in favor of magistrates' determinations of probable cause in order to avoid giving police an incentive to resort to warrantless searches in the hope of relying on consent or some other exception to the warrant requirement that might develop at the time of search." Abeyta, 795 P.2d at 1327-28.
Here, even resolving all doubts in the magistrate's favor, we conclude that the informant's statements do not provide a substantial basis for issuing the warrant in this case. On its face, the affidavit fails to establish the informant's basis for knowledge. As in Pacheco, the affidavit in this case contains no information regarding how the informant knew that defendant was selling ilegal drugs. See Pacheco, 175 P.3d at 95. The informant did not state that he bought drugs from defendant or that he witnessed any sales of drugs by defendant. He did not state that he had been in defendant's presence during a sale. Nor did the informant provide any other basis for his assertions, as he did not state that he had been inside defendant's trailer or had witnessed defendant handling large amounts of either methamphetamine or cash. Further, the affidavit does not reflect that the informant's reliability is bolstered because he previously gave *7reliable information to the police or made a declaration against his penal interest. See Randolph, 4 P.3d at 482 n. 2.
Moreover, although the informant provided some details about defendant's alleged activities, the details that police corroborated, such as defendant's identity and place of residence, did not relate to or describe criminal activities. See Abeyta, 795 P.2d at 1327; see also People v. Leftwich, 869 P.2d 1260, 1268 (Colo.1994) (police corroboration of facts that were "neither suspicious nor difficult to obtain and could merely be based on rumors and hearsay" insufficient to establish probable cause). Although the informant was "right about some things," we conclude that these factual details were insufficient to allow a judge to reasonably conclude that the informant had access to reliable information about the illegal activities reported to the police. See Abeyta, 795 P.2d at 1327. As in Pacheco, 175 P.3d at 95, little or no degree of suspicion attaches to the particular corroborated noncriminal information provided by the informant here.
In addition, the information alleging generalized criminal activity, even if taken at face value, was stale by the time the search warrant was issued in this case. The affidavit must establish probable cause to believe that contraband or evidence of criminal activity is located in the place to be searched at the time of the warrant application, not merely at some time in the past. Miller, 75 P.3d at 1112. Here, as in Miller, the informant's description of criminal activity was nearly one month old by the time the affidavit was executed. Moreover, even if we were to read the affidavit's description of the informant's statement to mean that the described criminal activities of defendant took place on a nightly or ongoing basis-so as to render the information not stale but current-the observations of suspicious activity described by the deputy, discussed below, were made one month after the informant provided his tip. The affidavit contains no information about police attempts to ascertain whether the reported illegal activity was ongoing at any time before March 20, 2007. See id. at 1114.
Neither independently nor in combination with the other allegations in the affidavit does the informant's information provide a substantial basis for finding probable cause.
2. Deputy's Observations
The affidavit describes the following events, occurring on March 20, 2007, approximately one month after the deputy was provided with the informant's information. At 11 pm. that night-a few hours before the warrant was issued and the search conducted-the deputy apparently conducted surveillance on defendant's trailer. The deputy observed a white sedan with one occupant momentarily park across the street from the trailer before parking directly in front of it. The driver left the vehicle running with the lights on as he exited the car, holding a cell phone to his ear. He walked around to the back of defendant's trailer and, about five to ten minutes later, drove away.
Although corroboration of non-criminal activity may in certain cireumstances support a finding of probable cause, see People v. Turcotte-Schaeffer, 843 P.2d 658 (Colo.1993), we conclude that these observations of non-criminal activity, even coupled with the information provided by the informant, do not provide a substantial basis for the warrant. "If vague, unverifiable allegations accompanied by verifiable, innocuous facts can result in a warrant, the constitutional requirement that a search warrant only issue upon probable cause becomes a nullity." Leftwich, 869 P.2d at 1268.
Nothing which the deputy observed corroborated any of the specific information supplied by the informant. Most noticeably absent is any indication that the observed individual had contact with defendant or obtained anything from, or placed anything in, the "fake rock" described by the informant. In fact, there is no mention by the deputy of observing the "fake rock"-the one arguably verifiable incriminating detail provided by the informant-in or near defendant's trailer. Moreover, there is no basis to conclude that the described activity was unusual or suspicious as the affidavit does not indicate whether the deputy conducted surveillance of the trailer park on occasions other than this one.
*83. Two Arrests
According to his affidavit, after observing the above activity, the deputy followed the driver of the white sedan, saw him make a turn signal violation, and initiated a traffic stop. 'The deputy subsequently arrested the driver for traffic violations and an outstanding warrant. During a search of the driver, the deputy found two silver, serew-top containers that held substances he believed to be marijuana and methamphetamine. A search of the vehicle yielded additional suspected drugs and drug paraphernalia. The driver stated that he had just come from his brother's house and that his brother lived with defendant. The deputy's affidavit also states that at the location of the traffic stop the deputy arrested another individual for possession of drug paraphernalia and marijuana, but provided no discernible connection between the second individual and defendant.
We conclude that the cireumstances of these arrests fail to establish a "direct link" between illegal drugs and defendant's trailer. See Leftwich, 869 P.2d at 1268. Although the deputy had observed one of the arrestees engaged in activities in the vicinity of defendant's trailer, the arrestees provided no information indicating that they had obtained the seized substances from defendant or from defendant's premises, or even that they had had any contact with defendant. Nor was any information implicating defendant obtained regarding the driver's observed cell phone usage. Moreover, as noted above, the deputy did not see the arrestees acquire anything from defendant or the "fake rock" described by the informant.
To the extent that the portion of the affidavit describing the arrests adds any weight in favor of a substantial basis to conclude that probable cause to search the trailer existed, we nonetheless conclude that under these circumstances the affidavit as a whole fails to provide a substantial basis.
4. Criminal History
After setting forth the above information, the deputy's affidavit concludes with two pieces of information obtained by running a background check on defendant. First, it states that in August 2006, about seven months earlier, defendant was a passenger in a vehicle in which police found methamphetamine under the driver's seat, leading to the driver's arrest. The affidavit does not state that any charges were filed against defendant or that any investigation of defendant followed the incident. Second, the affidavit states that in November 2003, several years before the warrant was issued, defendant pleaded guilty to possession of schedule II nareotics, without specifying the particular drug.
We conclude that these additional facts add no significant weight to the substantial basis determination in this case. Defendant was not charged with, or suspected of, criminal activity arising from the traffic stop at which he was present. And, as in Miller, where an arrest for a drug offense seven months before the issuance of a warrant was found stale, 75 P.3d at 1114, here too defendant's three-year-old conviction for an unspecified drug offense is stale.
Thus, we conclude that the information in the deputy's affidavit, considered separately and as a whole, failed to establish a substantial basis for the magistrate's determination that probable cause existed to issue the warrant.
B. Good Faith
If police execute a search warrant unsupported by probable cause, suppression of the evidence gained from the search is not required if the officers operated under the objectively reasonable belief that the warrant was legitimate. Leon, 468 U.S. at 922, 104 S.Ct. 3405; Randolph, 4 P.3d at 483. "The test for good faith is 'whether a reasonably well trained officer would have known that the search was illegal despite the magistrate's authorization, taking into account all of the cireumstances surrounding the issuance of the warrant." Pacheco, 175 P.3d at 96 (quoting Leon, 468 U.S. at 922-23 n. 23, 104 S.Ct. 3405). Even though the magistrate issued the warrant, "(aln officer may not automatically assume that a warrant is valid because a reviewing magistrate has executed it." Randolph, 4 P.3d at 483; see *9also People v. Altman, 960 P.2d 1164, 1170 (Colo.1998) (stating that in an ideal system, no magistrate would approve a defective warrant, but that because ours is not an ideal system, an officer must exercise his or her own judgment). Rather, "[this test imposes upon the officers involved in obtaining and executing a search warrant a continuing duty to exercise reasonable professional judgment." Randolph, 4 P.3d at 483.
However, by Colorado statute, an officer is presumed to have acted in good faith if he or she acted pursuant to a warrant. See § 16-3-808(4)(b), C.R.S8.2009. In Leon, the Supreme Court identified four circumstances in which an officer's reliance on a warrant would be unreasonable, and therefore not in good faith, and these four cireum-stances have been adopted in Colorado. See Pacheco, 175 P.3d at 96. Only the fourth circumstance is pertinent here: an officer's reliance on a warrant is unreasonable when the warrant is based on an affidavit so lacking in indicia of probable cause as to render official belief in its existence entirely unreasonable. Miller, 75 P.3d at 1114.
As in Randolph, the officer who conducted the search here was the same officer who prepared the deficient affidavit 4 P.3d at 484; see also Pacheco, 175 P.3d at 96. Although neither Randolph nor Pacheco establishes a per se rule that an officer relying on his own defective affidavit cannot establish that he was acting in good faith when executing the search warrant, here, as was determined to be the case in Randolph and Pacheco, we conclude that the deputy either knew or should have known that the warrant he obtained based on his own affidavit was lacking in probable cause, and thus it was objectively unreasonable for him to rely on it.
In Altman, a case upon which the prosecution relies and where the court concluded that the good faith exception applied, the court emphasized that the facts which were recited in the affidavit-and from which the officer inferred criminal activity connected to the defendant-were personally observed by law enforcement personnel. 960 P.2d at 1172; see also Miller, 75 P.3d at 1112 ("[The affidavit in Altman contained recent information the police had personally observed, suggesting a reasonable inference that the defendant was growing marijuana in his home."). Here, the prosecution argues that the observations personally made by the deputy support the information given by the unidentified informant. We disagree.
First, none of the deputy's personal observations confirm the informant's information. The deputy did not observe defendant selling drugs from a "fake rock"; indeed, the deputy did not observe a "fake rock." He did not observe defendant selling drugs or handling large amounts of cash, or any amount of cash.
Second, unlike in Altman, the deputy here did not personally observe, or describe in his affidavit, any suspicious conduct of defendant from which he could infer eriminal activity on defendant's part; indeed, he never stated that he observed defendant at all. Arguably, the deputy observed suspicious conduct by another near defendant's trailer, yet he provided no facts which connected this conduct to defendant.
We cannot conclude that good faith justified the deputy's execution of the search warrant in this case. Nor can we conclude that the seized evidence should nonetheless be admitted because, in these cireumstances, the deterrent purpose of the exclusionary rule would not justify exclusion of the evidence.
IV. Conclusion
The judgment is vacated. The order denying defendant's motion to suppress is reversed, and the case is remanded to the district court so that defendant may withdraw his conditional plea.
Judge ROY concurs. Judge DAILEY dissents.