Michael Mullen, Sex Offender Vigilante
The killer made it easy on the investigating agencies. He left fingerprints and ample cigarette butts to produce a full DNA sample. But the forensic evidence wasn't needed.
The big man could not contain his sense of accomplishment. A few days after the murder, he sent letters to police and the Bellingham Herald explaining his motives and threatening to kill more sex offenders who had targeted children.
"I only allowed James Allen Russell to live so he could get the message out to others of his kind that I am coming for him," he wrote to the Bellingham newspaper, using the nom-de-crime "Agent Life."
On Sept. 5, 10 days after the murder, the man telephoned police from a Bellingham restaurant to say he was prepared to surrender.
Within the hour, police had arrested Michael Anthony Mullen, 35, a 6-foot-5 ex-con and accomplished sad sack.
In a rambling confession, Mullen said he killed the two sex offenders in twisted retaliation for Duncan's alleged crimes. He added that he wished to protect children, including his own, from predatory pedophiles. Mullen said he got the names and home address of the sex offender roommates by visiting the county sheriff's Website about six weeks before committing the murders. He then carefully cased the house and concocted his FBI impostor scheme.
Mullen insisted that he wanted to immediately plead guilty and be sentenced to deathso he could meet Joseph Duncan in the afterlife and take revenge for his crimes against the Groene family.