Chicago police detectives are investigating after a woman was found dead in the Far Northwest Side home of a former Chicago police officer that was the scene of a 12-hour standoff last year.

The woman, 28, of northwest suburban Mount Prospect, was found unresponsive around 6 p.m. Saturday in a residence in the 6500 block of North Onarga Avenue in the Edison Park neighborhood, police said.

The Cook County medical examiner’s office has not ruled on the cause or manner of the woman’s death pending further review. Detectives are conducting a death investigation.

The former police officer called 911 after he discovered the woman lying on the floor, police said.

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The officer resigned from the Police Department in April, according to police spokesman Anthony Guglielmi. He had been placed on paid desk duty prior to his resignation.

He engaged in the lengthy standoff with police in March 2017. He was described as “distraught” at the time, but few other details were released. He was not criminally charged after the standoff, police said Monday.

Chicago Tribune’s Jeremy Gorner contributed.

mabuckley@chicagotribune.com