MANCHESTER, N. H.--A Medical School professor probably clinched a "not guilty" verdict for Dr. Hermann N. Sander here yesterday, in the opinion of veteran reporters at this nationally famous "mercy killing" trial.

Dr. Richard C. Ford '36, assistant professor of Legal Medicine at the Medical School and head of the Department of Legal Medicine, attacked four points in the state's case. Two hours of needling cross-examination could not shake his testimony.

It was Ford who, on January 21, performed the autopsy on the exhumed body of Mrs. Abbie Borroto. The state claims that Sander ended Mrs. Borroto's life as an act of merey, by injecting 40 cubic centimeters of air into the veins of his cancer stricken patient.

Lists Reasons

Sandwiching his dramatic statements between barrages of involved medical descriptions--which included chalk drawings and ten minutes of Kodachrome slides--Ford testified:

(1) That Dr. Sander's hypodermic needle didn't enter the vein in Mrs. Boroto's arm, because the vein had collapsed.

(2) If air had entered the vein, it couldn't have reached her heart, because a blod clot near the shoulder had cut off all circulation:

(3) Even if the air had reached her heart, it wouldn't have killed her, because 200 cc's of air is the smallest dose that will cause death.

(4) That even if the 40 cc's had killed Mrs. Borroto, she would then have died with "violent convulsions" and a lot of thumping"--which she didn't.

Alters Testimony

At the end of the afternoon, Ford had been forced, into only three minor revisions in his testimony: (1) the blood clot did not dam the whole vein, but just 95 percent; (2) a patient lying on her back needs somewhat less air to cause death; and (3) although the clot meant a slow strangulation of the blood stream, it didn't disprove sudden death by air.

The court adjourned with Ford still on the stand, and his cross-examination will resume this morning.