A federal court jury deliberated for 6 1/2 hours yesterday without reaching a verdict on whether Mary Treadwell used her now-defunct real estate firm to defraud the federal government and the impoverished tenants at the Clifton Terrace apartment complex of thousands of dollars to enrich herself.

The jury, comprising eight women and four men, told U.S. District Judge John Garrett Penn in a note early last night that it had "not reached any decision at this time." The jurors, who were meeting in a room without air conditioning, said they were "very uncomfortable" and asked to quit for the day.

Penn honored the request and told them to resume their deliberations tomorrow at 10 a.m.

The jurors started their deliberations late yesterday morning on the 21 conspiracy, fraud, false statement and tax evasion charges against Treadwell, the one-time president of P.I. Properties Inc., which managed and later owned Clifton Terrace in the mid-1970s.

In their note to Penn last night, the jurors asked that when they resume deliberations they be allowed to see all of the estimated 400 government reports, bank checks, notes, memos and charts that the judge admitted as evidence during the five-week trial. The jury, in a mid-afternoon note, had previously asked to see some of the central documents submitted as prosecution and defense evidence in the complex case.

Two of the documents requested by the jurors related to a key, sharply disputed issue at the trial: whether Treadwell, 42, sought to sell Clifton Terrace, a 285-unit apartment building, and turn it into a condominium, before P.I. Properties' 20-year mortgage with the Department of Housing and Urban Development had been paid off.

The government has contended that notes that Treadwell made at a June 1975 meeting indicated that she had no intention of maintaining Clifton Terrace for use by low- and moderate-income tenants, the purpose for which HUD sold the project to P.I. Properties.

Under HUD rules, if the agency ever attempted to foreclose on the mortgage, the buyer could keep from losing the property by paying off the entire mortgage and then would no longer have to follow the agency's rules to provide low- and moderate-income housing. It was a provision a HUD lawyer testified was a "legal loophole."

In the June 1975 meeting, Treadwell wrote, "20-year time reduced. Don't mention legal loophole."

Treadwell testified during 13 hours on the witness stand that the comment meant that she "felt no responsibility to tell HUD that they couldn't do a decent contract."

Moreover, Treadwell said that as HUD started to threaten P.I. Properties with foreclosure on the Clifton Terrace mortgage, because the firm rarely made payments on it, she sought to keep the project afloat with HUD and to forestall foreclosure. HUD eventually foreclosed in August 1978.

The defense introduced notes made by Treadwell's sister, Joan M. Booth, during a 1977 meeting showing that while Treadwell wanted to keep the HUD mortgage, P.I. Properties' general manager, Robert E. Lee, wanted to refinance the purchase with a private lender.

Treadwell and her court-appointed attorneys attempted to blame Lee and Booth, Clifton Terrace's project manager, for much of the wrongdoing that occurred during P.I. Properties' ownership of Clifton Terrace. Lee and Booth have pleaded guilty to conspiracy and other charges in the case, but were not called as witnesses at Treadwell's trial.

In addition to requesting notes from the two meetings, the jury asked for 12 allegedly false monthly financial statements that P.I. Properties submitted to HUD detailing expenditures at Clifton Terrace. The reports are the basis for 12 of the 16 false statement charges against Treadwell.

The jurors started their deliberations after Penn gave them long legal instructions on the meaning of the various charges in the case. The judge described a conspiracy as "a partnership in crime" and said that for Treadwell to be guilty, the jury would have to decide that she "knowingly became a member of that conspiracy."

But Penn also said that for a conspiracy to have existed, it was "not necessary" that the alleged conspirators "met or set their agreement in writing."