The 12 sequestered federal court jurors considering the fraud and conspiracy case against Mary Treadwell spent their day off Sunday by going to church, making trips to their homes to get fresh clothes, watching cable television and playing checkers and cards, all under the watchful eye of deputy U.S. marshals.

Yesterday, the jurors went back to work for their 13th day of deliberations in the eight-week-old trial. But when the jurors quit for the day early last night, after deliberating nearly 10 additional hours, they still had not reached a verdict.

The jury resumes its deliberations at 9 a.m. today.

The jury of eight women and four men has now spent nearly 100 hours--a record length for deliberations in a federal court case here--considering the 21 conspiracy, fraud, tax evasion and false statement charges against Treadwell, the 42-year-old former head of P.I. Properties Inc., a now-defunct real estate firm. She is accused of using the firm to defraud the federal government and the impoverished tenants at Clifton Terrace, which the company owned in the mid-1970s, of thousands of dollars to enrich herself.

The members of the Treadwell jury, along with five alternate jurors, have been sequestered since last Thursday night. U.S. District Judge John Garrett Penn ordered them sequestered earlier that day to make certain they did not see news accounts of how Treadwell abruptly and surprisingly stood up in court and said she wanted to change her plea of not guilty to no contest. Penn rejected the offer after a bench conference with Treadwell in which she admitted no guilt and claimed that "I won my trial."

Being a sequestered juror is something akin to being a prisoner, albeit without the stigma of going to jail. Each of the 17 has a private, single room at an undisclosed local hotel, but there are no working telephones or televisions in them. The government pays for lodging and three meals a day.

The jurors are permitted to talk with immediate relatives on the telephone and to receive mail from them, but marshals monitor their calls and mail to make sure the Treadwell case is not discussed. The jurors have also been allowed to watch television shows in a group, but a marshal has been stationed near the set to shut it off when any news report was broadcast.

Court clerk James F. Davey said the bill for the lodging and meals averages $70 a day for each juror, which means the tab for sequestering the Treadwell jury now totals more than $5,500.

Eleven of the 17 jurors--those who aren't government employes--were paid $30 a day for the first 30 days of the 41-day-old trial and $35 for each of the past 11 days. Each has now been paid $1,285.

Since government workers continue to receive their full regular salaries while they are on jury duty, the six jurors who work for the federal and D.C. governments have only been paid for the three Saturdays the jury has considered the case. All the jurors were paid for Sunday because they were sequestered, even though they did not work.

However, before they were allowed to go to church, the deputy marshals checked with the priests and ministers at the jurors' churches to make certain that the case would not be discussed from the pulpit.

Roger Ray, the chief deputy U.S. marshal here, said he has assigned eight deputies to help guard the Treadwell jury and monitor its out-of-court activities. In addition, he said additional deputies were called in Sunday to ferry the jurors to pick up clothing and personal belongings at their homes.

He said the total cost for the marshals' overtime pay won't be known until the verdict is reached and the jurors are released from the temporary custody of the U.S. government.