The defense began presenting its case yesterday in the trial of two University security guards accused of stealing Poland Springs water coolers from the Law School's Harkness Commons.

The guards, George D. Perry and Michael J. Auterio, are charged with larceny of property worth less than $100. Perry answered questions from his attorney yesterday in Middlesex County District Court, but was not cross-examined by the prosecution. The trial will conclude next Thursday with the cross-examination of Perry, the testimony of Auterio and closing arguments.

The case has divided the Harvard Police Department, with some officers testifying for the prosecution and others for the defense.

The prosecution acknowledged yesterday that the likelihood of a conviction is slim. A source close to the case said that assistant district attorney Mark A. Eichler had offered to continue the matter without a finding. The defense, confident of victory, declined the request.

The guards remain employees in good standing in the department, and their boss, Manager of Operations for Security Robert J. Dowling, testified yesterday that their reputations were "impeccable."

Asked as he left the court room yesterday what would happen if the guards were convicted, Dowling was confident.

"It's up to the University really," Dowling said. "I don't expect them to be convicted though."

Under questioning from the guards' attorneys, William P. Homans Jr. '41 and Matthew Buckley, defense witnesses testified that the room from which the two guards took the water coolers was reserved for trash.

Witnesses said the room was in disarray on Commencement Day last June, when the guards by their own admission removed the water coolers from the Law School. Theprosecution contends that the room was reservedfor recycled material and the water coolers wereHarvard property.

That contention, however, has been seriouslyundermined by revelations about the Harvard PoliceDepartment's investigation of the case. HarvardPolice Lt. John F. Rooney acknowledged duringearlier testimony in the case that informationsubmitted in an affidavit to secure a searchwarrant for the coolers was false.

And yesterday, Dowling and other defensewitnesses testified that as recently as July theroom had a sign on the door that said "TrashRoom--Do Not Lock." The sign has since beenremoved.

A civil suit by the two guards, who weresuspended without pay for about two months,appears likely. University Attorney Allan A. RyanJr., who is defending Harvard in a number of suitsby former and current police department employees,was in attendance for yesterday's testimony--as hewas two weeks ago when the prosecution presentedits case