Spokane County authorities continue to investigate a horrific discovery Tuesday near Nine Mile Falls.

Spokane County sheriffs said dispatchers received a phone call around 2:42 a.m. Tuesday morning from a man saying 27-year-old Jason Hart had killed his girlfriend. Authorities responded to a home 14800 block of West Autumn Lane in this small community northwest of Spokane around 11:30 a.m.

They briefly negotiated with Hart via a robot as he was originally believed to be armed and dangerous, but he surrendered about 30 minutes later. Sheriffs learned Hart was one of four people apparently living in the home, and when they searched the property they made a shocking discovery.

They found a woman's body immersed in a tub of acid in a garage on the property.  Haz-Mat teams were called as the substance was believed to be highly toxic. Information about what type of acid was in the tub and how long the victim had been in there was not released by authorities.

Hart has no prior criminal history, according to officials. They did not say if any charges were pending against the man, nor did they release the identity of the woman. An autopsy was scheduled for Wednesday.

Over the last decade, Nine Mile Falls (9-Mile as it's often referred to by residents) has increasingly become a bedroom community for people who commute to and work in Spokane.  It is the site of the popular Long Lake recreation area.