By this appeal filed pursuant to Mass.R.Grim. P. 30(c)(8),
The defendant was convicted of second degree murder and sentenced to life imprisonment on April 30, 1977. On May 6, 1977, he filеd a motion for a new trial based upon the assertion that the trial judge erred in admitting evidence of prior consistent statements of the sole identifying witness. The judge denied the motion, and the conviction was affirmed.
Commonwealth
v.
Saarela,
On August 3, 1981, the defendant filed a motion for a new trial. Contrary to the requirements of Mass.R.Crim.P. 30(c)(2),
*405
The Commonwealth filed two counter affidavits. Mass. R.Crim.P. 30(c)(3),
The second affidavit submitted by the Commonwealth was the affidavit of a ballistics expert who had testified for the Commonwealth at the original trial. He reiterated his opinion given at the trial to the effect that the bullets taken from the victim’s body were fired from the defendant’s rifle. In addition, he stated that he had observed Fassnacht perform tests with the rifle and that in his opinion those tests were conducted in an incorrect manner, causing erroneous results.
The motion was heard by the same judge who had presided at the trial. At the outset, the judge stated that he was not acquainted with Fassnacht or familiar with his background and invited comments from defense counsel in regard to those matters. Defense counsel responded that Fassnacht owned “Keystonе State Arms Consultants” and “is an expert in ballistics and is recognized as an expert. He has testified throughout the country, literally hundreds of times, your Honor. He is well qualified in this area.” In respоnse, the Commonwealth stated that “there are serious questions of Mr. Fassnacht’s competency, raised by the type of examination he conducted in this particular case.” The Commonwealth further indicated that it had witnesses who were available to testify at the hearing. Defense counsel also stated that Fassnacht would arrive shortly and be аvail *406 able to testify if there were any questions about his qualifications as an expert.
After listening to arguments of counsel in regard to the merits of the motion, the judge announced, frоm the bench, that the motion was allowed. The Commonwealth objected to the failure of the judge to hold an evidentiary hearing, and this appeal ensued.
1.
The lack of an evidentiary hearing.
The sole issue before us is whether the judge committed error in not holding an evidentiary hearing. The question raised is unique, as the prior cases have been concerned with the correctness of a judge’s decision in
denying
a defendant’s motion for new trial without holding an evidentiary hearing. See
Commonwealth
v.
Stewart,
In regard to a motion for new trial, it has been stated that “[t]he judge may decide the motion on the basis of affidavits without further hearing, ‘if no substantial issue is raised by the motion
or
affidavits’” (emphasis added).
Id.
at 257. Mass.R.Crim.P. 30(c)(3),
Here, the defendant submitted an affidavit, purportedly from an expert, that in substance challenged the ballistics evidence introduced by the Commonwealth at the trial. The Commonwealth countered with two affidavits, one of which was from the Commonwealth’s expert who had testified at the trial. Because the motion judge presided at the trial, he was familiar with the qualifications and background of the Commonwealth’s еxpert, in contrast to his admitted lack of familiarity with the qualifications of the defendant’s expert.
4
In addition, the Commonwealth’s expert
*407
had, by affidavit, directly challenged the methods by which Fassnacht had reached his сonclusions. Where, as here, “a substantial issue is raised and is supported by a substantial evidentiary showing, the judge should hold an evidentiary hearing.”
Commonwealth
v.
Stewart, id.
at 260. We therefore remand the case to the Superior Court for an evidentiary hearing in regard to the challenged ballistics evidence. In addition, the defendant must show that the evidence was “newly discovered.”
Commonwealth
v.
Cefalo,
2.
Other matters.
Therе are several other deficiencies in the present motion for a new trial that must be corrected before the motion properly may be heard on remand to thе Superior Court. The defendant must resubmit his motion for a new trial in accordance with the terms of Mass.R. Crim.P. 30(b) and (c),
The order granting the defendant’s motion for a new trial is reversed, and the originаl judgment of conviction is rein *408 stated. The defendant is to submit a new motion for a new trial and an evidentiary hearing is to be held on the challenged ballistics evidence and any other grounds as to which a substantial issue is raised by the affidavits.
So ordered.
Notes
The Commonwealth also raises as an issue that the judge abused his discretion in granting a new trial because the evidence was nоt “newly discovered.” At no time did the judge address this contention. We cannot decide the matter as the transcripts of the trial were not made part of this record. At the hearing on remand, the judge must decide, among other things, whether the evidence is newly discovered.
In
Commonwealth
v.
Saarela,
In the affidavit the affiant stated that he was prepared to offer at the hearing on the motion photographs comparing individual matching markings on the cartridge casing with those on test cartridges, and a video cassеtte tape of a microscopic examination, of the bullets, cartridge casing, and rifle.
As noted, at the outset of the hearing on the motion the judge stated to defense counsel that he was not acquainted with Fassnacht or familiar with his background. After rendering the decision, from the bench, *407 allowing the motion, the judge, some days later, filed a memorаndum in regard to his decision. In the memorandum, the judge made a finding that Fassnacht was an expert. We are at a loss, on the basis of the record before us, to ascertain the sоurce of the evidence upon which the judge premised this finding. Certainly, he could not rely on the unsupported statements of counsel made during the course of argument, espеcially where the qualifications of the defendant’s expert witness were challenged.
We note, for instance, that, during the course of his argument to the judge on the motion, defense counsel stated that he had developed information that the victim’s blood had coagulated by the time the police arrived at the scene. The judge, in his memorandum, аdopted defense counsel’s statement as a finding of fact. No affidavit was submitted by defense counsel in regard to this ground. If defense counsel desires to offer evidence on this ground at the hearing, he must submit an affidavit to support his contention.
Commonwealth
v.
DeMarco,
