Ottersen opened fire, killing Bret Berlin, 44, and wounding a woman. The victims were sitting in a parked car at the time.
Then Ottersen led police on a high-speed pursuit from the island to I-5 and south to Mukilteo. In that city, he reportedly crashed and drew the gun on police, and was shot by officers.
Ottersen died a few weeks later at a Seattle hospital. He was 34.
Two different investigations into the day's violence are ongoing.
The Island County Sheriff's Office is investigating the double shooting on Camano Island.
The Snohomish County Multiple Agency Response Team, or SMART team, is investigating the Mukilteo shooting, a standard procedure when police use fatal force.
The Island County sheriff's investigation is wrapping up, detective Ed Wallace said. Because Ottersen, the sole suspect, is dead, no criminal court case is expected to follow.
At the hospital, Ottersen was too gravely injured to speak with detectives before he died.
“We were not able to determine the motive,” Wallace said. “The surviving victim couldn't shed any light on what happened. (Ottersen) was a heroin addict. We don't know why. (The surviving victim) couldn't tell us why.”
Investigators believe that Ottersen and the Camano Island shooting victims ran in the same circles and had mutual friends, but there was no other known connection among them.
Evidence collected in the case, including ballistics, supported the woman's story of what happened, Wallace said.
She and Berlin were sitting in a car in the 500 block of Michelle Drive at about 3:15 p.m. when Ottersen approached the driver's side window and asked for cigarettes.
One of them handed Ottersen a pack of cigarettes. Ottersen grabbed the pack and then “pulled out a firearm and without warning or provocation shot (Berlin) in the head,” detectives were told.
The bullet went into the left side of the man's face and out the right side of his neck, according to court papers. The same bullet went through the woman's arm.
The SMART investigation into the Mukilteo shooting also is ongoing, pending additional reports from the county medical examiner's office, said Mark Marsh, an agency spokesman and Edmonds police sergeant.
Ottersen's handgun was recovered at the Mukilteo scene. Investigators have not said whether he shot at police before they opened fire. Upon completion, SMART investigations are reviewed by prosecutors to determine if the fatal force was justified.
Ottersen had no felony history in Washington.
He'd had two previous interactions with Island County deputies, officials said.
He was given a ticket in February 2013 for a headlight-related traffic violation. Police also were summoned that June for reports that Ottersen was threatening suicide.
Rikki King: 425-339-3449; firstname.lastname@example.org.
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