Closing arguments in the trial of the Boston doctor accused of murdering his wife of 32 years were postponed Monday after the court received a last-minute fax from a woman that claims to have encountered a sweating, dazed man in her yard the morning of the murder.

"He was in a total daze. He was just not aware that we were even there," Jacqueline Swerling told a packed courtroom, minus the jury. "He turned around and he was sweating. He just kind of walked up near our road. He just went on about his business."

Swerling, who lives with her partner Richard Acherson about two miles from the park in which Mabel Greineder was killed, said she saw the man as she drove into her driveway with Acherson the morning of Oct. 31, 1999. The man was wearing shorts and looked as if he had been running. She faxed Judge Paul Chernoff Monday morning, saying she wrote a letter to the Wellesley, Mass., police department on Nov. 2, 1999, about their experience but never heard back. Police say they never received the letter.

Chernoff, who has put the jury under sequestration, apologized after the lunch break and dismissed jurors for the rest of the day before moving into an emergency voir dire hearing.

The judge must now decide whether this information, if given to both sides before the trial and presented to the jury, could changed the outcome of the case of Dirk Greineder, 60, who is charged with first-degree murder.

Greineder says he briefly walked ahead of his wife, 58, during a stroll the morning she was bludgeoned and stabbed to death. His lawyers claim the police failed to consider the possibility of a serial killer, noting that two other people had been killed in nearby Massachusetts parks around the time Greineder's wife was slain. But the judge ruled early in the trial that the defense would not be allowed to present its serial-killer theory to the jury.

The prosecution claims Greineder killed his wife to be free to pursue his secret life of porn and prostitution.

During a brief questioning session, Chernoff asked Swerling, who said she couldn't remember if she had mailed the letter to the police department after faxing it, why she hadn't followed up on the letter.

"I can't tell you how many times I've wanted to find the name of the attorney for the family," Swerling said. "I figured that [the police] didn't think it was relevant.

Later Monday evening, Acherson took the stand out of the presence of the jury and confirmed Swerling's account, although he could not remember exactly when the fax had been sent.

Explaining his reason for coming forward, Acherson told the judge, "There was just some doubt in our minds that Dr. Greineder could have done this based on our knowledge of this person [in the yard] and the location of the pond. There was some doubt in our minds that this person who we had never seen before could be an unknown assailant."

Wellesley police chief Terrence Cunningham also testified during the emergency voir dire. "I've never seen this letter before," he said.

He told the judge that Swerling, an admitted former alcoholic, had been in contact with his department about 25 times since 1993 for offenses including DUI and a range of domestic disturbances.

Chernoff said he would decide Tuesday morning whether he would allow Swerling to tell her story to the jury, but added that he expected the case to go to the jury Tuesday afternoon.

Earlier, defense attorney Martin Murphy rounded out his week-long defense case by calling Colin Greineder, 26, who said that as early as May 1997 he was aware of his father's frequent use of Internet pornography sites.

"I felt embarrassed, and I was sad, I was just sad," the younger Greineder told the jury as his dad's face fell. Colin Greineder testified that, while living at home with his parents, he stumbled across a hidden cache of pornography kept by his father on the family computer.

He detailed an attempt to cover his own tracks in the Internet browser's history file — a place where a record of Internet use is kept on each computer — which actually revealed sex sites his father had visited. "It looked like there were a lot," he said.

Although Colin Greineder told the jury "Pornography is not a big deal to me," the experience hit home, he said. "I wanted to tell my dad. I wanted somehow to confront him."

After his discovery, Colin Greineder began to monitor his father's use of Internet pornography and realized the habit was sporadic, he said. He also began paying close attention to the relationship between his parents.

Colin Greineder

He once asked his mother, Mabel Greineder, whether she and his father were having problems. "She said 'Yes, the sex life could be better ... I think your dad has his own way of dealing with that now," Colin Greineder told the jury.

Despite their marital problems, Colin said, his parents seemed to get along well. "After that my parents continued to work as a parenting team," he said. He told the jury he felt like "You had two parents that loved you no matter what."

He called his mother "the center of our family. She was the one that taught the rest of us how to care for one another. She was the person I felt closest to in the whole world."

Colin also gave his father's defense a boost on factual evidence, testifying that he purchased a box of nails during the week that his mother was killed. The nails are a key issue because one of the murder weapons, a two-pound sledgehammer, was purchased three minutes after a receipt found in the Greineder household showed that a box of nails was purchased.

The prosecution says Dirk Greineder bought the nails the same day he bought the sledge. When showed a picture of the nails and the receipt, Colin said he couldn't recall if those were the nails that he used. But he said, "I have a memory of buying those nails, or nails like those."

Defense lawyer Murphy rested without calling the third of the Greineder children, 28-year-old Britt. But on rebuttal, prosecutor Grundy called the curly blonde to the stand to ask about her testimony earlier when the trial was in its grand jury phase.

But whereas Colin Greineder was an able witness, jovial at times and solemn at others, his sister was too tearful to provide much information for either side.

In a quick cross-examination of a witness many suspected he would have called, Murphy established that Britt Greineder was overwhelmed the day of her grand jury testimony.

"What was your frame of mind when you testified to the grand jury?" asked Murphy.

"I think I was just really upset," she said. "I was really a mess. I was in shock. To be honest, I couldn't testify to anything that I said that day. I was really upset."

Grundy also called Martin Foley, a trooper with the Massachusetts State Police, who testified that the nails found in Greineder's belongings did not match the nails Colin said he purchased.

Belinda Markell, Mabel Greineder's niece, also took the stand, suggesting that Mabel Greineder suspected that her husband was having an affair long before the murder.

Earlier in the trial, Greineder said his wife once discovered some Viagra in a travel kit and questioned him about the impotence cure-all, but then apologized for "prying" into his affairs. He said the two had stopped having sex in 1990.

The trial is being broadcast by Court TV.