Detective David Blackmer is accused of creating a salacious Facebook page purporting to be the girlfriend after the pair went through a messy breakup.
Police say after the couple ended their relationship, the victim went to Blackmer's Everett home on July 17 and confronted him in front of his family.
Blackmer, who's 43-years old and has been with the department for 17 years, then created the fake Facebook page as retaliation, according to police.
Police say the page was filled with suggestive pictures and threatening posts.
"There was information presented on this phony account that would cause any reasonable person fear," said Sgt. Sean Whitcomb with the Seattle Police Department.
The victim found the page and filed a complaint with the Seattle Police Office of Professional Accountability. She told investigators the Facebook page caused her fear and embarrassment, according to police.
OPA investigators turned the case over to detectives in the Special Operations Bureau, who looked into the matter and found enough to arrest Blackmer on suspicion of identity theft and domestic violence/cyberstalking.
"Truly, it doesn't get a whole lot more serious than felony domestic violence, which is what he has been booked for and specifically in this case, identity theft," Whitcomb said.
Police are working with the Snohomish County Prosecuting Attorney's Office because the alleged crimes occurred in Snohomish County.
Blackmer, who was most recently assigned to the department's Criminal Investigations Bureau, has been placed on paid administrative leave. If he's charged with a felony, his status will change to unpaid administrative leave, according to police.