NASHUA, N.H. – A teenager accused of murdering a woman and injuring her daughter with a machete during a home invasion knew details of the crime that only the killer could have known, a prosecutor said Monday during closing arguments.

Letters written by 18-year-old Steven Spader in jail amount to a confession, said Jeffery Strelzin, the lead prosecutor in the case.

“This defendant is so proud of what he did, he couldn’t shut up,” Strelzin said of the 15 pages of letters Spader allegedly wrote. “These are his words: ‘I hacked at the mom. Death doesn’t frighten me, blood excites me.’ Page after page of vivid detail only the killer would know about the slaughter of a mother and attempted slaughter of her daughter.”

His attorney countered that Spader’s words are in keeping with his reputation for exaggerating and lying.

“If there is one thing we have learned in this case, it’s that Steven Spader cannot be trusted,” Jonathan Cohen told jurors.

Jurors will hear instructions on the law this morning before they begin weighing whether Spader is guilty of first-degree murder and other felonies.

Prosecutors say Spader wielded a machete and co-defendant Christopher Gribble used a knife to hack to death 42-year-old Kimberly Cates and maim her 11-year-old daughter, Jaimie, in their Mont Vernon home in October 2009.

Spader has pleaded not guilty to charges of first-degree murder, attempted murder and other felonies. If convicted of first-degree murder, he faces an automatic sentence of life in prison without parole.

Cohen assailed the credibility of three co-defendants who brokered plea deals and testified against Spader. He suggested they, not Spader, were involved in the attacks.

Strelzin took a machete from an evidence table and raised it toward the jury before pointing it directly at Spader.

“He’s a coward and a killer,” Strelzin said, his voice raised, as he glared at Spader. “You can trust that.”

Spader’s parents were in the courtroom for the closing arguments. His mother, Christine Spader, told reporters outside the courthouse: “We love our son. God loves our son too.” His father repeatedly told reporters to leave them alone.

Jurors heard from 45 witnesses during the nine-day trial – all presented by the state. The defense called no witnesses.

As he delivered his final arguments, Strelzin projected smiling images of Kimberly and Jaimie Cates on a large screen. He reminded jurors of the medical examiner’s testimony that Kimberly Cates was alive for all 32 wounds inflicted on her, including ones that cleaved her skull and shattered her jaw.

Strelzin lauded Jaimie’s courage in feigning death, then dragging herself to the kitchen to phone police.

“She showed more strength in that room that morning than he will ever show in his entire life,” Strelzin said.

Spader, who was 17 at the time of the attacks, sat expressionless throughout the nearly four hours of final arguments by both sides.

If jurors do not return a verdict by the close of court Wednesday, they face a four-day break in their deliberations.

Gribble is due to go on trial in February.