Several of the jurors considering the conspiracy case against Mary Treadwell were inclined initially to acquit her, two said yesterday, but later decided she was guilty because she wrote a note in 1975 indicating she might turn the low-income Clifton Terrace apartment complex into a condominium.

In the note, Treadwell, then the president of P.I. Properties Inc., a now-defunct real estate firm, reminded herself not to mention a "legal loophole" by which the company could have paid off its 20-year mortgage on Clifton Terrace before it was due. The firm then would not have had to provide housing for impoverished tenants, as it had agreed to do when it bought the property from the federal government.

Jury foreman Norman C. Washington, 50, a computer systems analyst, and Magaleane Coleman, 40, a Howard University Hospital secretary, both said they were among a group of jurors who in the initial stages of their record 131 hours of deliberation wanted to acquit Treadwell of the key conspiracy charge, but changed their minds when they considered the 1975 note.

Washington described the group as "a few" jurors, while Coleman said it was initially a majority of the 12 jurors.

These and other details of the marathon deliberations of the eight women and four men considering the case against Treadwell emerged yesterday as several jurors recounted the painstaking and elaborate procedures that they said took longer than even they had expected, but finally led to their conclusions.

The jury convicted Treadwell Friday of conspiring to use P.I. Properties to defraud the federal government and the Clifton Terrace tenants of thousands of dollars to enrich herself, as well as of seven charges that she made false statements in six reports and a letter she or her firm sent to U.S. Department of Housing and Urban Development officials.

Treadwell, 42, was acquitted of 13 other charges. She faces up to 40 years' imprisonment and fines totalling $80,000 for her convictions. John W. Nields Jr., Treadwell's court-appointed attorney, said the eight convictions will be appealed.

After the jury announced its verdict, completing 17 days of deliberations, Nields contended that the decision came as a result of the jury's "confusion and compromise."

But Washington, Coleman and four other jurors yesterday rejected that notion and instead said that the complexity of the case, along with their careful and lengthy examination of the evidence, caused the deliberations to extend far beyond the participants' expectations.

"We wanted to feel good and be able to look anyone in the face and say we did the best we could," said Oblie A. Willis, 70, a retired fitting room attendant at the Woodward & Lothrop department store. "We wanted to reach a verdict. We didn't want a hung jury."

Despite the length of the deliberations, several of the jurors agreed that at no time were they deadlocked.

Juror Randolph W. Tritell, 30, a Federal Trade Commission attorney, said, "I wouldn't even use the term deadlocked . We would discuss various issues until it didn't seem fruitful anymore," then move on to another charge or issue if agreement couldn't be reached, returning later to the more difficult issues.

Coleman said the jurors decided "within the first three or four hours" after they began their deliberations on July 9 that at least some P.I. Properties officials conspired to use the firm to defraud the federal government and the Clifton Terrace tenants. Two other former P.I. Properties officials, Robert E. Lee, the firm's general manager, and Joan M. Booth, Treadwell's sister and the Clifton Terrace project manager, have pleaded guilty to conspiracy and other charges in the case and are awaiting sentencing.

The much more difficult question, one that took several days to decide, was whether Treadwell knowingly participated in that conspiracy, the jurors said.

The question was so difficult, some of the jurors said, that they decided to reach a verdict first on three charges that Treadwell evaded more than $33,000 in federal income taxes from 1976 to 1978. Treadwell had filed all three returns in 1980 and actually claimed more income than federal investigators found that she had earned in the three years, although she admits she still owes the $33,000.

The jurors acquitted her of the three counts, according to Coleman, because "we did not feel filing late was tax evasion. She didn't try to hide her income."

"I think she went broke," said Willis, in explaining why she felt Treadwell did not pay the taxes.

The jurors said they then dealt with the 16 false statement charges against Treadwell, deciding nine of them in her favor and convicting her on the other seven.

Twelve of those false statement charges involved P.I. Properties' monthly financial reports to HUD on the Clifton Terrace operation. The jury acquitted Treadwell on half those charges and convicted her on the other half. But jury foreman Washington said their mixed conclusions on the false statement charges were not the result of compromise.

Rather, he said, the differing verdicts came because on six of the reports the jurors found discrepancies on income P.I. Properties claimed to have received or money it had spent. On the six others, he said, they did not find such discrepancies.

"Everyone looked at, I'd say, 95 percent of the documents," said juror Linwood Toomer, 47, a mailman. "When you are deliberating and there are points to be made, negative or positive, the only way you can do this is to check it out. If you get a bill from Hecht's and think it's too much, you check it out."

One such document was the key 1975 Treadwell memo.

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 no longer would have to follow the agency's rules to provide low- and moderate-income housing."

In a June 1975 meeting, Treadwell wrote in a note to herself, "20-year time reduced. Don't mention legal loophole."

Treadwell testified that the comment meant she "felt no responsibility to tell HUD that they couldn't do a decent contract."

But juror Coleman said she wondered, "Why find loopholes if you're not going to use them?"

While the jurors uniformly said they did not fight in the jury room and became friends during their long deliberations, they expressed relief that their ordeal was finished, particularly so they could again eat home-cooked meals.

The food brought to the jurors in the courthouse, said foreman Washington, "was the pits."