Concurring Opinion by
Spaeth, J.:The reason for suppressing evidence is to deter improper police conduct. Mapp v. Ohio, 367 U.S. 643 (1961). Thus, every police officer is required to know that he cannot search without probable cause. If he nevertheless searches on mere suspicion, the court will ignore his argument that the result of the search justified the suspicion. Ker v. California, 374 U.S. 23, 40, n. 12 (1963); United States v. Di Re, 332 U.S. 581, 595 (1948); Commonwealth v. DeMichel, 442 Pa. 553, 277 A.2d 159 (1971). To accept the argument would encourage another officer to do what he knew he should not do, in the hope that his illegal conduct would likewise be excused by its result.1
*188The majority upholds the arrest because the police “could reasonably have believed” that a felony — burglary — had been committed. The point, however, is not what the police could have believed, but what they did believe. If what they did believe was that only a misdemeanor had been committed, they must, or should, have known that they had no right to make a warrantless arrest. Commonwealth v. Reeves, 223 Pa. Superior Ct. 51, 297 A.2d 142 (1972). We should not reward such conduct, and encourage it in others, by retroactively finding a justification for it. Cf., Henry v. United States, 361 U.S. 98 (1959); Commonwealth v. Jeffries, 454 Pa. 320, 324, n. 6, 311 A.2d 914, 917, n. 6 (1973).
In the present case, what the police did believe was that a theft — not a burglary — had been committed. It is true that an officer of the Williamsport police, who made the initial stop, testified that “[t]here was something like I said, about a burglary or theft or something, concerning something with trailers in the Montoursville area.” (N.T. 7.) However, when the hearing judge asked the Chief of the Montoursville police “[W]hat offense did you believe had been committed?”, the Chief replied, “Larceny from the mobile houses, theft from the mobile homes.” (N.T. 19.) Furthermore, the sergeant of the Montoursville police who signed the criminal complaint accused appellant of “THEFT.”
At this point, the case sails into rather deep waters. “Theft” is “a felony of the third degree if the amount involved exceeds $2000.00” or if the property stolen is of a certain sort, such as a firearm or automobile, or if, in a case of receiving stolen property, the receiver is in the business of buying or selling stolen property. All other “thefts” are misdemeanors, either of the first, second, or third degree. Crimes Code, Act of Dec. 6, 1972, P.L. 1482, No. 334, §1, eff. June 6, 1973, 18 Pa.C.S. §3903. Accordingly: If the police believed they were arresting appellant for a felony theft, they did not need a warrant; but if they believed they were arresting for a mis*189demeanor theft, they did need a warrant. The difficulty is that here what the police believed was that the theft might be either a felony or a misdemeanor — which it was they could not be sure.
It is true that there is no express testimony that this was what the police believed. However, the record is plain enough. The radio message was “that there was a van on Charles Street, removing items from a mobile homes [s-ic]” (N.T. 13). The message did not describe the number or sort of items. The recipient was left to wonder whether the items were of considerable or small value; one interpretation of the message was as reasonable as the other. Thus, the question presented by this case is this: When an officer cannot tell whether a felony or a misdemeanor has been committed, does he need an arrest warrant?2
I do not know of any case that answers this question. It seems to me, however, that it may be answered by drawing an analogy with the law of warrantless searches.
Generally speaking, warrantless searches are not to be encouraged. “It is well settled ... that a search conducted without a warrant issued upon probable cause is ‘per se unreasonable ... subject only to a few specifically established and well-delineated exceptions.’ ” Schneckloth v. Bustamonte, 412 U.S. 218, 219 (1973) (citations omitted). Similarly, warrantless arrests should not be encouraged. If, therefore, an officer does not know whether a felony or misdemeanor has been committed, *190he should, generally speaking, assume that the offense is a misdemeanor, and get a warrant.
This rule, however, cannot be more than general; it must be subject to some exception, just as is the rule regarding warrantless searches. The exceptions to the rule regarding warrantless searches have recently been summarized by Judge Hoffman in his dissenting opinion in Commonwealth v. Cubler, 236 Pa. Superior Ct. 614, 621, 346 A.2d 814, 819-20 (1975). As there observed, the rationale of all of the exceptions is that certain circumstances will be recognized as sufficiently “exigent” to excuse the officer from the requirement that he get a warrant. Applying this reasoning by analogy to the present case, it seems to me that the officers who arrested appellant were not required to get a warrant. Although they did not know whether the theft was a felony or a misdemeanor, they did have reason to believe that the theft might be a felony, that the items stolen were in the van, and that if they did not make the arrest at once, the van would be driven away and the items would become unrecoverable. Together these circumstances were sufficiently exigent to excuse the general requirement of a warrant.
I therefore agree that the order of the lower court should be reversed and the case remanded for further proceedings.
. For discussion of the basis of the exclusionary rule, see Monaghan, The Supreme Court, 1974 Term — Foreword: Constitutional Common Law, 89 Harv. L. Rev. 1, 3-10 (1975).
. For theft arrests occuring after October 17, 1974, this issue will no longer arise. On that date, Section 3904 was added to the Theft chapter of the Crimes Code. The section provides:
“A law enforcement officer shall have the same right of arrest without a warrant for any grade of theft as exists or may hereafter exist in the case of the commission of a felony.” Act of Dec. 6, 1972, P.L. 1482, No. 334, §3904, added Oct. 17, 1974, P.L. 749, No. 251, §1.
Here the arrest was on May 27, 1974.