Appellant Theriault was convicted of escaping from custody while held as a federal prisoner in the city jail at Mobile, Alabama. We reverse because the trial judge erred in refusing to authorize employment at government expense of a psychiatrist to examine defendant under the provisions of 18 U.S.C. § SOOGACe).1
April 28, 1969, Theriault’s appointed counsel filed a motion pursuant to Rule 28, Fed.R.Crim.P. and 18 U.S.C. § 4244, requesting that defendant be examined by a psychiatrist who could testify as an expert witness for the defense, to determine defendant’s mental capacity at the time of the alleged offense and currently. The court granted the request by ordering that Theriault be taken before a qualified psychiatrist at the United States Penitentiary, Atlanta, Georgia, where he was imprisoned, who should examine him as to competency at the time of the offense and competency to stand trial.
Before Theriault was examined he filed an objection, again referring to Rule 28 and § 4244, alleging that, because of his employment by the government, the prison psychiatrist had an adverse interest. At the same time defendant renewed his request for examination by a psychiatrist who could testify as an expert and otherwise assist defense counsel. Before these matters were ruled on, and still prior to any examination, defendant moved under 18 U.S.C. § 3006A (e) that the court authorize defense counsel to employ a psychiatrist of Mobile, Alabama, (where Theriault’s case would be tried) to examine defendant and be available to appear as an expert witness as to defendant's mental condition. The motion pointed out that defendant’s indigency already had been established, and alleged that appointment of an expert as requested was necessary to an adequate defense. The motion was denied August 11 with a notation “Psychiatrist already appointed by previous order.”
The psychiatrist at the Atlanta prison commenced examination of defendant July 9. On September 4 Theriault moved for reconsideration of the denial of his § 3006A(e) motion. September 9 the Atlanta psychiatrist submitted to the court his report with copies for the prosecutor and for defense counsel. His conclusion was that Theriault was not insane at the time of the offense. At the beginning of trial on September 15 the District Judge held an ex parte hearing on the motion for reconsideration and adhered to his earlier denial, pointing out that one of his reasons was the problem, while Theriault was outside the penitentiary walls, of safeguarding against his escape (Theriault had a long record of previous escapes).
At trial defendant admitted “withdrawing himself” from the jail. His principal defense was insanity. He claimed that previously he had been treated inhumanely while imprisoned at Parchman state prison in Mississippi, and that he was unable to control his impulses to escape from the Mobile jail because of his overpowering fear that he would be sent back to Parchman and again be mistreated. Also he claimed that conditions in the Mobile jail were not tolerable, contributing to his uncontrollable impulses to escape.
Por testimony to support his defense of insanity Theriault relied on members of his family, prison inmates subject to easy impeachment, and the chaplain of *715the Atlanta prison (whose testimony was not favorable to the defense). As a rebuttal witness the government employed the Atlanta prison psychiatrist, over defense objections that an examination made under § 4244 may not be employed against the defendant pleading insanity. His opinion was that defendant probably was competent at the time of the alleged offense and suffering only from “dissocial behavior.”
The court erred in denying the § 3006A (e) motion without conducting the ex parte proceeding required by the statute.2 Also it could not properly deny appointment of an expert sought under § 3006A(e) on the basis that an earlier appointment had been made under § 4244.3 Sec. 4244 concerns examination to determine if the defendant is competent to stand trial. The court appoints a psychiatrist who examines the accused and reports to the court. Rule 28 authorizes the court to appoint its own expert witness, who is expected to be neutral and detached. He advises the parties of his findings. See Rule 28 and Wright, Federal Practice and Procedure, § 452. The § 3006A(e) expert fills a different role. He supplies expert services “necessary to an adequate defense,” which embraces pretrial and trial assistance to the defense as well as availability to testify. His conclusions need not be reported to either the court or the prosecution.
The impartial expert appointed under Rule 28 at the request of defense counsel to inquire into defendant’s sanity is not a prosecution witness but the court’s witness and he may testify as to his findings. United States ex rel. Smith v. Baldi, 192 F.2d 540 (3d Cir.), aff’d, 344 U.S. 561, 73 S.Ct. 391, 97 L.Ed. 549 (1953). Thus the original request by Theriault’s counsel, resting in part on Rule 28, made the prison psychiatrist’s testimony admissible on the issue of competency at the time of the alleged offense.4 Theriault’s subsequent request for a § 3006A(e) expert to assist the defense did not deprive the court of power to proceed with the Rule 28 examination, and to use the information obtained therefrom. Defendant’s objection to the prison psychiatrist based on alleged adverse interest is not tenable. The doctor was subject to cross-examination on possible interest and bias, but he was not incompetent to testify.
The standards to govern what is “necessary to an adequate defense” are not susceptible of arbitrary articulation but can best be developed on a case by case basis. Schultz v. United States, 431 F.2d 907 at 913 (8th Cir. 1970) (concurring opinion). Usually the appellate court will be reviewing a trial court denial of a § 3006A (e) motion in the light of only the information available to the trial court at the time it acted on the motion. But in this instance the application was denied because of the earlier appointment, and without the statutorily mandated hearing. There was no focus on necessity of an expert to prepare and present an adequate defense. On remand it will not even be necessary for the court to conduct a hearing, because at the appellate level we are in the unusual position of having before us a complete trial record, which establishes with as much clarity as one could want the necessity of a *716§ 3006A(e) psychiatric expert to assist the defense in preparing for and presenting its case at another trial. The District Court should enter an order authorizing the employment.
Numerous claims of error in admissibility of evidence either are without merit or concern matters which should not arise at another trial. The claim of a variance between the proof and the bill of particulars also can be eliminated before trial.
Reversed and remanded for further proceedings not inconsistent with this opinion.