Michael Contee, Jr., was charged under three indictments with armed rob*326bery, under Sections 2901 and 3202, Title 22, District of Columbia Code (1951). After a trial by jury in the United States District Court he was found guilty and sentenced. These appeals followed.
I
Our examination of the record has brought to our notice a serious question which was not urged in the briefs or oral argument, namely, whether the trial court erred in failing to suppress certain evidence seized by the police from appellant’s rooms. Under Rule 52(b) of the Federal Rules of Criminal Procedure, 18 U.S.C.A., we can, of course, notice “Plain errors or defects affecting substantial rights * * * although they were not brought to the attention of the court.”
The record discloses that early in the trial the prosecution called Officer Douglas of the Metropolitan Police. He testified that at about 3:30 in the morning of January 3, 1952, he went to appellant’s house and knocked on the door. Appellant replied, he said, by asking “Who is it?” Douglas responded, “It is the police.” A long interval passed. Douglas knocked again and said, “Come on, open up.” During the interval Douglas heard “a door being pushed open near the rear of his room and a sliding sound on the floor.” Appellant finally opened the door and the officer arrested him. Douglas opened the door in the rear of the room and found a Navy jacket, a target pistol, and other objects, all in a box inside the adjoining room. Douglas questioned appellant about these objects and was told by the latter that he had found them in Rock Creek Park. Douglas also asked appellant about a number of holdups, but appellant denied having taken part in them. The officer took appellant and the jacket and other objects to the police station, and turned him and the effects over to the Robbery Squad. Douglas further testified that he came to look for the appellant because — and this, he said, was his only source of information — a man bad told him that Contee “was the party that had been involved in some robberies * * * I don’t know the man’s name even. He was a man that lived in the neighborhood, apparently, and knew Contee.” This man was not, Douglas said, one of the complaining witnesses. Early in the course of the examination of the officer, appellant’s court-appointed attorney said, “I will have to object to this testimony unless it is established he had probable cause to make an investigation.” The court replied that there had been no motion to suppress. Counsel answered, “I was not aware of all this evidence.” The objection was overruled.
At the conclusion of Douglas’ testimony appellant’s counsel said, “In spite of the fact that a motion to suppress was not filed, I think it was clear that the evidence in question taken by the officer was illegally seized and should not be admitted in evidence.” The court then said, “I am going to overrule your motion, both on the ground it should have been made before, because the rules seem to contemplate that, but, even so, I think in view of the fact there was a voluntary offering of it to him, it is proper.” After further colloquy, the court overruled the objection as to the admission of the coat. It sustained the objection as to certain cartridges and a wallet, evidently on the ground that these latter had not been sufficiently identified.
Rule 41(e) of the Federal Rules of Criminal Procedure provides that a motion to suppress evidence unlawfully obtained “shall be made before trial or hearing unless opportunity therefor did not exist or the defendant was not aware of the grounds for the motion, but the court in its discretion may entertain the motion at the trial or hearing.”
We think that under all the circumstances of the present case the court erred in denying the motion to suppress. In the first place, it seems clear that the property in question was illegally seized, in violation of the Fourth Amendment. There was no search warrant, and no arrest warrant. We think it *327plain as a matter of law that the appellant did not freely consent to the search. Johnson v. United States, 1948, 333 U.S. 10, 68 S.Ct. 367, 92 L.Ed. 436; Higgins v. United States, D.C. Cir., 1954, 209 F.2d 819; Judd v. United States, 1951, 89 U.S.App.D.C. 64, 190 F.2d 649. The Government now argues that the search may be justified as an incident of the arrest under the doctrine of United States v. Rabinowitz, 1950, 339 U.S. 56, 70 S.Ct. 430, 94 L.Ed. 653. But to justify the search on this ground the arrest itself must be valid. United States v. Rabinowitz, supra, 339 U.S. at page 60, 70 S.Ct. 430. Here it clearly was not. The question is — did the officer making the arrest have probable cause to believe that the person arrested had committed an offense? See Mills v. United States, 90 U.S.App.D.C. 365, 196 F.2d 600, certiorari denied, 1952, 344 U.S. 826, 73 S.Ct. 27, 97 L.Ed. 643. As we have seen, the officer here testified that an individual who “lived in the neighborhood, apparently, and knew Contee” was his sole source of information. An uncorroborated tip by an informer whose identity and reliability are both unknown does not constitute probable cause to make an arrest.1 ******Nor is any exceptional circumstance alleged to have existed here: there is no suggestion that appellant would have escaped, or that there was any necessity for apprehending him in the small hours of the morning.
In the second place, we think the motion to suppress was timely made. Appellant’s attorney — appointed by the court- — stated that he was not aware of the seized evidence. This statement by counsel would appear to satisfy, prima facie at least, the provision of the rule allowing a motion to be made during trial if the defendant “was not aware of the grounds for the motion.” The court made no inquiry to test the validity of counsel’s statement, but denied the motion without further questioning. If it had questioned further it would have found that the defendant had been adjudicated mentally incompetent shortly after his apprehension and that he had spent nearly a year thereafter in mental institutions under circumstances to be discussed presently. True, some element of neglect on the part of counsel may have entered in. But under the circumstances we must give the accused the benefit -of the doubt, and hold that the court’s peremptory rejection of counsel’s statement was erroneous. We think that it was plain error affecting substantial rights, within the meaning of Rule 52(b). The conviction must be reversed and a new trial granted.
II
In this disposition of the case we do not reach the questions posed by counsel in their briefs and argument.2 Nor do we need to canvass at length the issue, briefed and argued by counsel at our request, of appellant’s fitness to stand trial.
After appellant’s apprehension and arraignment, the District Court appointed counsel to represent him. Counsel moved that appellant receive a mental examination, and the court on February 12, 1952, ordered him committed for that purpose. Physicians’ reports were received on March 4 and March 6, advising the court that appellant was of unsound mind and suffering from de*328mentía praecox. The United States Attorney thereupon moved the court for a judicial determination of the mental competency of the accused, pursuant to 18 U.S.C. § 4244 (1952), on the basis of the physicians’ reports. An inquisition under that statute was held by the court on March 14, during which testimony was received from both doctors. The court found appellant “presently insane and so mentally incompetent as to be unable to understand the proceedings against him, or properly to assist in his own defense.” Appellant was then committed to St. Elizabeths Hospital. On January 29, 1953, the Superintendent of the Hospital addressed a letter to the Attorney General of the United States which said, in part, that “It has now been determined that Michael M. Contee, Jr., is mentally competent to stand trial and is able to consult with counsel and properly assist in his own defense.” Appellant was then removed to the District of Columbia jail, and without further order of the court was brought to trial on March 3, 1953. This procedure was erroneous, for the reasons stated in Gunther v. United States, 1954, 94 U.S. App.D.C., 215 F.2d 493. Before appellant is again tried, a judicial determination of his competency to stand trial should be made.
III
One other matter seems to us to require comment. While the case was pending here we inquired of the United States Attorney, by order to show cause, why the Director of the Bureau of Prisons had not acted pursuant to the provisions of 18 U.S.C. § 4245 (1952) with respect to this appellant, in view of numerous indications in the record before us that appellant had long been suffering from mental illness. That section provides a procedure for the relief of convicted persons incarcerated in Federal prisons who, there is probable cause to believe, were mentally incompetent at the time of their trials.3 In such a case, after the Director of the Bureau of Prisons has made an appropriate certificate, the District Court wherein the conviction was had holds a hearing to determine the mental competency of the accused at the time of the trial. However, a proviso in Section 4245 limits its application to cases where “the issue of mental competency was not raised and determined before or during * * * trial.” The United States Attorney in his return stated that it was the view of the Bureau of Prisons and its Director that this proviso barred the application of Section 4245 to Con-tee, since in his case “a proceeding had been had under 18 U.S.C. § 4244, et seq., and a certificate had been made to the District Court on January 29, 1953, that Contee was competent to stand trial * * We think this position erroneous as a matter of law. In appellant’s case no judicial determination had been made of the kind of which the proviso in Section 4245 speaks, namely, that he was competent to stand trial. On the contrary, he was the subject of a judicial determination that he was incompetent to stand trial, followed simply by *329an administrative finding of competency. Under these circumstances the benefits of Section 4245 should not have been denied him if he was otherwise entitled to them. Our disposition of these appeals, however, makes it unnecessary for us to enter any order on this subject.
The judgments of the District Court will be
Reversed, and new trial granted.
. Worthington v. United States, 6 Cir., 1948, 166 F.2d 557; Brown v. United States, 9 Cir., 1925, 4 F.2d 246; United States v. Clark, D.C.W.D.Mo.1939, 29 F.Supp. 138; United States v. Tom Yu, D. C.D.Ariz.1932, 1 F.Supp. 357; United States v. Baldocci, D.C.S.D.Cal.1930, 42 F,2d 567. But cf. Husty v. United States, 1931, 282 U.S. 694, 51 S.Ct. 240, 75 L.Ed. 629; United States v. Li Fat Tong, 2 Cir., 1945, 152 F.2d 650; Coupe v. United States, 72 App.D.C. 86, 113 F. 2d 145, certiorari denied, 1940, 310 U.S. 651, 60 S.Ct. 1105, 84 L.Ed. 1417.
. Appellant’s original brief and argument urged that the trial was a nullity because of the lack of a formal arraignment and because certain instructions to be given the jury as requested by appellant were denied.
. The full text reads:
“Whenever the Director of the Bureau of Prisons shall certify that a person convicted of an offense against the United States has been examined by the board of examiners referred to in title 18, United States Code, section 4241, and that there is probable cause to believe that such person was mentally incompetent at the time of his trial, provided the issue of mental competency was not raised and determined before or during said trial, the Attorney General shall transmit the report of the board of examiners and the certificate of the Director of the Bureau of Prisons to the clerk of the district court wherein the conviction was had. Whereupon the court shall hold a hearing to determine the mental competency of the accused in accordance with the provisions of section 4244 above, and with all the powers therein granted. In such hearing the certificate of the Director of the Bureau of Prisons shall be prima facie evidence of the facts and conclusions certified therein. If the court shall find that the accused was mentally incompetent at the time of his trial, the court shall vacate the judgment of conviction and grant a new trial.”