DEDHAM -- Accused murderer Thomas Lally took the witness stand in his own defense Monday in a dramatic finish to his trial, saying his friendturned-accuser Jason Weir was the real killer of another friend's elderly great-aunt.

Lally, 24, of Norton, said in Dedham Superior Court that he was too afraid of Weir, who turned 21 Monday, to tell the police Weir had murdered Mari na Calabro, 84, after the killing in her Quincy apartment in December of 2001.

`` I had nothing to do with Marina's death,'' Lally testified. `` Jason Weir killed her.''

When asked by his lawyer, Robert Griffin, whether he took part in planning her murder, Lally replied, `` I never planned to harm her or anyone else.''

Prosecutors say Lally fatally bludgeoned the retired hairdresser with a frying pan and tea kettle in the kitchen of the apartment before moving her body to the bottom of a flight of stairs to make the murder look like an accident. The murder was committed so Lally, Weir and Anthony Calabro, 22, could share $260,000 and a portion of the proceeds from the elder Calabro's house, which Anthony Calabro stood to inherit upon his great-aunt's death, prosecutors allege.

After initially being ruled an accidental death, authorities reopened the investigation in October 2002 when a friend of Weir's went to police, leading to the arrest of Weir, Lally and Calabro.

Lally defended himself even under an intense cross examination by Assistant District Attorney Susan Corcoran, during which both the defendant and the prosecutor raised their voices and cut each other off.

Lally stood on the witness stand for about two hours bracing himself with both hands, making frequent eye contact with the 16-member jury, which was seated to his left.

Lally testified he was in the kitchen the morning of Dec. 19 getting ready to leave Marina Calabro's apartment when Weir entered carrying a frying pan in his right hand, which was covered by a sock.

He said he was about 10 feet away when Weir suddenly struck the woman two or three times.

`` At first I was in shock. I said `What are you doing?' I tried to help by getting between them but she fell to the floor unconscious,'' Lally testified.

He said he struggled with Weir and was scratched in the face after Weir twisted the elderly woman's neck.

`` He told me I was just as guilty as he was because I was there with him. If I went to the police he said he'd take us all down,'' Lally testified.

Months later, he added, Weir threatened to harm his family if he told anyone. During his testimony, Weir, who reached an agreement with the prosecution to testify in return to a lesser sentence for manslaughter, said Lally killed Calabro with a frying pan while he stood helpless in fear of Lally.

When Lally was asked about comments other witnesses attributed to him about killing Marina Calabro, Lally said he was trying to be `` sarcastic.''

`` Anthony was always complaining about his aunt, so I said that so he would stop whining,'' Lally testified.

To blunt allegations that he needed money, Lally testified that he was receiving annuity payments from his biological father's estate in addition to working.

He said his biological father died when he was a young child.

Lally testified that he received $14,000 in 2001 and was schedule to receive up to $118,000 by 2016.

Months after Marina Calabro's death, Lally said he told friends Jason Weir killed her and was blackmailing Anthony Calabro.

After his arrest in October 2002, Lally said he told police what happened, but `` they brushed it off.''

When asked under cross examination whether he blamed Calabro for the murder during his interrogation in October 2002, Lally said he had no recollection of saying that.

The prosecution called state police Detective Lt. Kevin Shea as a rebuttal witness who contradicted Lally about statements police said he made after his arrest.

However, when asked by Griffin, Shea said the interview was not videotaped or recorded.

When Lally was told police had a statement from Weir in addition to a wiretapped recording of Weir telling a friend what happened, Shea said Lally put his head down in his hands.

`` He said `All I wanted to do was be a corrections officer with my father at Walpole State Prison,'' Shea testified.

Lally's father, Stephen Lydon, and his sister, Jeni-Lyn Lydon, gave testimony to cast doubt on Weir's credibility.

Weir lived in Lally's home before and after the murder before moving out after a series of quarrels with Lally, according to testimony.

Closing arguments in the trial that has lasted seven days are scheduled for Wednesday.

Anthony Calabro has pleaded innocent to murder. His case is scheduled for a pretrial conference April 5 and may go to trial in the middle of May, his lawyer, Robert Launie, said.