A man accused of killing his wife and two of her relatives in a tiny Montana town has told authorities that a stranger must have broken into the house they shared and shot the victims.

The claim from 39-year-old Robert James LeCou was contained in an affidavit released Thursday by Carbon County District Attorney Alex Nixon.

Authorities allege LeCou shot his wife, his wife's sister and a brother-in-law on April 5 in Belfry before fleeing. He was arrested in Washington state three days later.

LeCou's public defender in Washington has not responded to requests for comment.

Nixon says LeCou won't fight extradition to Montana to face charges.

Authorities have added a charge of tampering with evidence to the three counts of deliberate homicide that LeCou faces.