NASHUA, N.H. (CBS/AP) – A teenager who helped hide evidence in a deadly New Hampshire home invasion and machete attack says he also provided an alibi for Steven Spader.

20-year-old Autumn Savoy testified Friday against Spader, 18, the first person to go on trial for murder in the case.

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Prosecutors say Spader killed Kimberly Cates and maimed her 11-year-old daughter in their home.

Savoy has pleaded guilty to hindering prosecution and conspiracy and will be sentenced to five to 19 years in prison.

He told police Spader was at his house the night of the attacks and described Spader as “bouncy” and “happy, excited” after announcing that he had killed two people.

Just hours after the killings, Spader, Savoy, and Christopher Gribble are seen buying breakfast and cigarettes at a convenience store.

WBZ News Radio’s Bernice Corpuz files her report from Nashua, N.H.

Savoy told the jury Spader and Gribble came to his house because he’d agreed to provide an alibi in the wake of the attacks.

Savoy has said Spader told him the burglary was an initiation rite for his brotherhood, the Disciples of Destruction.

He told jurors he rode with Spader and Gribble to the Nashua River, and at their instruction, threw the bag of clothing into the river.  He also said he sorted jewelry taken from the Cates home, which Spader and Gribble would take to a pawn shop.

While watching a TV show about a fictional serial killer, Savoy said Spader boasted of killing Kimberly Cates.  He said Spader told him 11-year-old Jaimie ran, jumping over her mother, but was stabbed by Gribble. 

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He said Spader told him at one point he became bored, and hacked the girl across the face with a machete.

Savoy said at Spader’s suggestion, he searched for news accounts of the home invasion and learned Jaimie Cates had in fact survived.

Asked how Spader reacted to learning that, Savoy told the jury he mocked Gribble, saying, “You’re an idiot because you can’t even kill a fifth grader.”

Defense attorneys got Savoy to admit he joked about it, too.

Earlier in Friday’s session, a witness testified Spader threatened to kill him if he talked to police.

Eldon Spikes told the court Spader waved a knife at him hours after the attack.

Spikes said he heard Spader and co-defendant Christopher Gribble brag about the murder and how they were planning to kill again.

Spikes’ testimony clashes with prior statements he gave police and the grand jury.

On cross-examination, he admitted he told police he had taken a near-lethal dose of prescription drugs and couldn’t remember the weekend.

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