Deputies say five people were shooting guns along the Nooksak River last June when one of the bullets hit 23-year old Alyssa Smith, who was at a barbeque at her dad's house in the 6100 block of Gadwa Road near Ferndale.
Smith and the rest of the party heard bullets flying over their heads and called police. As Smith walked toward the house to take cover, deputies say she was hit in the chest with a bullet.
She was taken to St. Joseph Hospital in Bellingham, where she died the next morning.
Deputies arrived moments later. They heard the gunfire and traced the shots to a group of five people on the other side of the Nooksack River, who admitted they had been shooting handguns and high-powered rifles.
Two members of the group, 40-year-old Douglas Quiding and 23-year-old Robert Lee, were arrested for unlawful possession of a firearm. Both men have been convicted of felonies in the past.
For the next eight months, deputies continued to investigate which of the five men actually fired the fatal shot. With help from forensic experts at the Washington State Crime Lab, deputies developed probable cause to arrest 31-year-old Nicholas Zylstra of Lynden.
Investigators believe Zylstra was firing a rifle from the hip in a method called "bump fire," which allows a "semi-automatic weapon to be fired in a manner that simulates fully automatic fire," according to deputies.
The bullet that killed Smith was also matched to the rifle that Zylstra had been firing.
On Thursday, Zylstra turned himself in at the Sheriff's Office and was booked into Whatcom County Jail on suspicion of first degree manslaughter. He's being held without bail.