delivered the opinion of the Court.
Petitioner Whiteley, in 1965, was convicted in the District Court for the Second Judicial District of the State of Wyoming on charges of breaking and entering and being an habitual criminal.1 Both at his arraignment and at trial Whiteley challenged the constitutionality of the use of evidence seized during a search incident to an arrest which he claimed was illegal. The trial court overruled petitioner’s motion to suppress, and on appeal the Supreme Court of Wyoming affirmed. Whiteley v. State, 418 P. 2d 164 (1966). This proceeding commenced with a petition for habeas corpus in the United States District Court for the District of Wyoming, which was denied on November 25, 1968.2 Whiteley v. Wyoming, 293 F. Supp. 381. On appeal, the United States Court of Appeals for *562the Tenth Circuit affirmed. Whiteley v. Meacham, 416 F. 2d 36 (1969). We granted certiorari, limiting the writ to the issue of the constitutionality of the arrest and ensuing search and seizure. 397 U. S. 1062 (1970).3 We reverse the judgment of the Tenth Circuit for the reasons stated herein.
I
The circumstances surrounding petitioner’s arrest and the incidental search and seizure, as stated by the Wyoming Supreme Court, 418 P. 2d 164, 165-166, are as follows:4
“On November 23, 1964, certain business establishments in Saratoga were broken into, including the Rustic Bar and Shively’s Hardware, the offenses being investigated by the Carbon County Sheriff [Sheriff Ogburn] who, acting on a tip, the next day signed a complaint charging defendant and another with breaking and entering the building identified *563as the Rustic Bar. This complaint was made before a justice of the peace at approximately 11:30 a. m. on the 24th, and a warrant issued. After the investigation, the sheriff put out a state item on the radio to pick up two suspects of the breaking and entering, defendant and another. The message went to the network at Casper and was transmitted over the State, received by the Albany County Sheriff’s Office and communicated to the Laramie Police Department, the message giving names and descriptions of the two persons and advising the type of car probably being driven and the amount of money taken, including certain old coins with the dates. Late at night on November 24, a Laramie patrolman, in reliance on the information in the radio item, arrested the defendant and his companion. At the time, the patrolman had no warrant for defendant’s arrest nor search warrant. The officer together with a deputy sheriff, who had come up in the meantime, searched the car and removed a number of items introduced in evidence, including tools and old coins, identified at the trial as taken from Shively’s Hardware. . . .”
Sheriff Ogburn’s complaint, which provided the basis for the arrest warrant issued by the justice of the peace, is as follows:
“I, C. W. Ogburn, do solemnly swear that on or about the 23 day of November, A. D. 1964, in the County of Carbon and State of Wyoming, the said Harold Whiteley and Jack Daley, defendants did then and there unlawfully break and enter a locked and sealed building [describing the location and ownership of the building].” App. 28.
A state item 881, the bulletin which Sheriff Ogburn *564put out on the radio and which led to petitioner’s arrest and search by the Laramie patrolman, is as follows:
“P & H for B & E Saratoga, early A. M. 11-24-64. Subj. #1. Jack Daley, WMA, 38, D. O. B. 2-29-[26], 5'10", 175, med. build, med. comp., blonde and blue. Tat. left shoulder: 'Love Me or Leave Me.’ #2. Harold Whitley, WMA, 43, D. O. B. 6-22-21, 5' 11", 180, med. build, fair comp, brown eyes. Tat. on right arm 'Bird.’ Poss. driving 1953 or 1954 Buick, light green bottom, dark top. Wyo. lie. 2-bal. unknown. Taken: $281.71 in small change, numerous old coins ranging from ,5‡ pieces to silver dollars, dated from 1853 to 1908. Warrant issues, will extradite. Special attention Denver. . . .” App. 31.5
II
The decisions of this Court concerning Fourth Amendment probable-cause requirements before a warrant for either arrest or search can issue require that the judicial officer issuing such a warrant be supplied with sufficient information to support an independent judgment that probable cause exists for the warrant.6 Spinelli v. United States, 393 U. S. 410 (1969); United States v. Ventresca, 380 U. S. 102 (1965); Aguilar v. Texas, 378 U. S. 108 (1964); Rugendorf v. United States, 376 U. S. 528 (1964); Jones v. United States, 362 U. S. 257 (1960); Giordenello v. United States, 357 U. S. 480 (1958). In the instant case — so far as the record stipulated to by the parties *565reveals7 — the sole support for the arrest warrant issued at Sheriff Ogburn’s request was the complaint reproduced above.8 That complaint consists of nothing more than the complainant’s conclusion that- the individuals named therein perpetrated the offense described in the complaint. The actual basis for Sheriff Ogburn’s conclusion was an informer’s tip, but that fact, as well as every other operative fact, is omitted from the complaint. Under the cases just cited, that document alone could not support the independent judgment of a disinterested magistrate.
The State,9 however, contends that regardless of the sufficiency of the complaint to support the arrest warrant, the Laramie police officer who actually made the *566arrest possessed sufficient factual information to support a finding of probable cause for arrest without a warrant. In support of this proposition, the State argues that a reviewing court should employ less stringent standards for reviewing a police officer’s assessment of probable cause as a prelude to a warrantless arrest than the court would employ in reviewing a magistrate’s assessment as a prelude to issuing an arrest or search warrant.10 That proposition has been consistently rejected by this Court. United States v. Ventresca, 380 U. S., at 105-109; Aguilar v. Texas, 378 U. S., at 110-111; Jones v. United States, 362 U. S., at 270-271. And the reason for its rejection is both fundamental and obvious: less stringent standards for reviewing the officer’s discretion in effecting a warrantless arrest and search would discourage resort to the procedures for obtaining a warrant. Thus the standards applicable to the factual basis supporting the officer’s probable-cause assessment at the time of the challenged arrest and search are at least as stringent as the standards applied with respect to the magistrate’s assessment. See McCray v. Illinois, 386 U. S. 300, 304-305 (1967).
Applying those standards to the instant case, the information possessed by the Laramie police officer at the time of arrest and search consisted of: (1) the data contained in state bulletin 881, reproduced supra; (2) the knowledge, obtained by personal observation, that two men were driving a car matching the car described in the radio bulletin; (3) the knowledge, possessed by one of the arresting officers, that one of the people in the car was Jack Daley, App. 71; (4) the knowledge, acquired *567by personal observation, that the other individual in the car fitted the description of Whiteley contained in state bulletin 881; and (5) the knowledge, acquired by the officer after stopping Whiteley, that he had given a false name.11
This Court has held that where the initial impetus for an arrest is an informer’s tip, information gathered by the arresting officers can be used to sustain a finding of probable cause for an arrest that could not adequately be supported by the tip alone. Draper v. United States, 358 U. S. 307 (1959). See Spinelli v. United States, 393 U. S. 410 (1969). But the additional information acquired by the arresting officers must in some sense be corroborative of the informer’s tip that the arrestees committed the felony or, as in Draper itself, were in the process of committing the felony. See the opinions of the Court and that of Me. Justice White concurring in Spinelli v. United States, supra, and p. 423. In the present case, the very most the additional information tended to establish is that either Sheriff Ogburn, or his informant, or both of them, knew Daley and Whiteley and the kind of car they drove; the record is devoid of any information at any stage of the proceeding from the time of the burglary to the event of the arrest and search that would support either the reliability of the informant or the informant’s conclusion that these men were connected with the crime. Spinelli v. United States, supra; McCray v. Illinois, supra; Aguilar v. Texas, supra.
*568The State, however, offers one further argument in support of the legality of the arrest and search: the Laramie police relied on the radio bulletin in making the arrest, and not on Sheriff Ogburn’s unnamed informant. Clearly, it is said, they had probable cause for believing that the passengers in the car were the men described in the bulletin, and, in acting on the bulletin, they reasonably assumed that whoever authorized the bulletin had probable cause to direct Whiteley’s and Daley’s arrest. To prevent arresting officers from acting on the assumption that fellow officers who call upon them to make an arrest have probable cause for believing the arrestees are perpetrators of a crime would, it is argued, unduly hamper law enforcement.
We do not, of course, question that the Laramie police were entitled to act on the strength of the radio bulletin. Certainly police officers called upon to aid other officers in executing arrest warrants are entitled to assume that the officers requesting aid offered the magistrate the information requisite to support an independent judicial assessment of probable cause. Where, however, the contrary turns out to be true, an otherwise illegal arrest cannot be insulated from challenge by the decision of the instigating officer to rely on fellow officers to make the arrest.
In sum, the complaint on which the warrant issued here clearly could not support a finding of probable cause by the issuing magistrate. The arresting officer was not himself possessed of any factual data tending to corroborate the informer’s tip that Daley and Whiteley committed the crime.12 Therefore, petitioner’s arrest vio*569lated his constitutional rights under the Fourth and Fourteenth Amendments; the evidence secured as an incident thereto should have been excluded from his trial. Mapp v. Ohio, 367 U. S. 643 (1961).
Ill
There remains the question as to the proper disposition of this case. The State urges us to remand so that it will have an opportunity to develop a record which might show that the issuing magistrate had factual information additional to that presented in Sheriff Ogburn’s complaint. Brief for Respondent 8-9. Yet the State concedes, as on the record it must, that at every stage in the proceedings below petitioner argued the insufficiency of the warrant as well as the lack of probable cause at the time of the arrest. Brief for Respondent 4. Knowing the basis for petitioner’s constitutional claim, the State chose to try those proceedings on the record it had developed in the state courts. See n. 4, supra. Its sole explanation for this state of affairs is that “the state has felt, based on precedent and logic, that no court would accept the legal reasoning of petitioner.” Brief for Respondent 9. In the circumstances of this case, that justification, as we have shown, is untenable.
Pursuant to our authority under 28 U. S. C. § 2106 to make such disposition of the case “as may be just under the circumstances,” we reverse the judgment of the Tenth Circuit and remand with directions that the writ is to issue unless the State makes appropriate arrangements to retry petitioner.13 Cf. Giordenello v. United States, 357 U. S., at 487-488.
It is so ordered.
He was given concurrent sentences on the breaking and entering charges of one to 10 years and, in consequence of the recidivist charge, imprisonment for life.
Prior to commencing federal habeas corpus proceedings, Whiteley had filed a petition for post-conviction relief pursuant to the Wyoming statutes. No appeal was taken from the denial of that petition.
In his petition for habeas corpus, Whiteley raised several other issues which had previously been advanced in his state petition for post-conviction relief, but not in his direct appeal to the Supreme Court of Wyoming. On these other issues, both lower federal courts held that failure to appeal the denial of his state post-conviction petition constituted nonexhaustion of state remedies. Petitioner sought to raise the exhaustion issue in his present petition for certiorari, but, as noted in text, we granted the writ limited to the search and seizure issue decided by the lower federal courts.
At the outset of the federal habeas corpus proceeding now before us, both parties entered into the following stipulation, App. 10:
“IT IS HEREBY STIPULATED by and between the parties through their respective counsel that, pursuant to the agreement of the parties in open court on February 16, 1968, both sides will rely exclusively on the record before the trial court in the original case of the State of Wyoming v. Harold Whiteley . . . and any and all parts of the record on appeal to the State of Wyoming ... in the hearing on the merits of this case before the [U. S. District Court].”
A second version of state item 881 is identical in all relevant respects except that it omits reference to the arrest warrant. See App. 37.
In Ker v. California, 374 U. S. 23 (1963), the Court held that the same probable-cause standards were applicable to federal and state warrants under the Fourth and Fourteenth Amendments. In Mapp v. Ohio, 367 U. S. 643 (1961), the Court held the exclusionary rule was applicable to state prosecutions.
See n. 4, supra.
The dissent seems to imply that “this record shows” that Sheriff Ogburn received the description of the car contained in the radio bulletin from someone who also informed him that he also saw the car at the scene of the crime. Post, at 570. The record wholly fails to support any such implication. Sheriff Ogburn, who testified on four separate occasions at the trial, see R. 105-112, 187-191, 310-314, 335-337, said nothing of the sort. Only one other witness, Leonard Russell Marion, testified to having given Ogburn any information about the car prior to Whiteley’s arrest; Marion never testified to seeing the car near the scene of the crime. R. 317-322, 329-330. Indeed, it is quite apparent from reading Marion’s testimony that his observations of Whiteley on the day of the robbery took place at his own house. R. 320-321.
More importantly, even the dissent apparently concedes that as far as the record in this case reveals, the only information Sheriff Ogburn communicated to the magistrate issuing the warrant was contained in his written complaint reproduced above. Under the cases of this Court, an otherwise insufficient affidavit cannot be rehabilitated by testimony concerning information possessed by the affiant when he sought the warrant but not disclosed to the issuing magistrate. See Aguilar v. Texas, 378 U. S. 108, 109 n. 1. A contrary rule would, of course, render the warrant requirements of the Fourth Amendment meaningless.
Since this is a federal habeas corpus proceeding, the State is technically not a party.
“The legal principles relied upon by the state throughout this entire litigated process have been based on the premise that a law enforcement officer may make a warrantless arrest if he has requisite probable cause, which can be something less than the requisite probable cause that must be presented to a judicial officer prior to the issuance of an arrest or search warrant.” Brief for Respondent 6.
After arresting Whiteley and Daley, the officers searched the car and discovered in the car’s interior the old coins taken in one of the burglaries and described in the radio bulletin. In addition, they found burglar’s tools in the trunk of the car. Of course, the discoveries of an illegal search cannot be used to validate the probable-cause judgment upon which the legality of the search depends.
The arrest warrant issued at about noon on November 24, 1964. See App. 53. State bulletin 881 was broadcast at 3:03 p. m. that same day. App. 31. It is apparent that Sheriff Ogbum did not himself acquire additional corroborative data possibly supporting a probable-cause arrest after securing the warrant.
The State makes a halfhearted attempt to argue that the introduction of the illegally seized evidence was harmless error. The *570evidence, of course, was damning, to say the least. See n. 10, supra. The only other evidence implicating Whiteley was his accomplice’s testimony. It is clear that the error cannot be said to be harmless under applicable standards. Chapman v. California, 386 U. S. 18 (1967); Harrington v. California, 395 U. S. 250 (1969).
Contrary to the implications in the dissenting opinion, see post, at 571, no witness at trial other than the accomplice placed Whiteley “near the scene of the crime” on the night of the robbery.