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Suspect in killing of Denver woman walking dog pleads not guilty by reason of insanity

Michael Close faces 22 charges for the June 10 shooting of 21-year-old Isabella Thallas and her boyfriend in the Ballpark neighborhood.

DENVER — The man accused of killing a woman and seriously injuring her boyfriend while they were walking their dog in the Ballpark neighborhood pleaded not guilty by reason of insanity in court Monday.

Michael Close, 37, faces 22 charges in the June 10 incident, including first-degree murder and using a banned high-capacity magazine.

He made his plea in court at 8:30 a.m. during a continuation of a Jan. 4 arraignment hearing and he will undergo a mental health evaluation at the Colorado Mental Health Institute of Pueblo.

A court hearing for a status check is scheduled for 8:30 a.m. on May 10.

> Video above from January: Denver Police Department Chief Paul Pazen discusses Isabella Thallas murder.

Isabella Thallas died in the shooting just days after her 21st birthday. Her boyfriend, 26-year-old Darian Simon, was seriously injured.

According to the arrest affidavit in the case, Close fired at the couple after Simon told their dog to relieve itself near his apartment building in the 2900 block of North Huron Street.

Close was later arrested in Park County. The Denver Police Department (DPD) said an AR-15 and a handgun were found in the passenger-side floorboard of the Mercedes SUV he was driving at the time, as well as a gun belt and firearm magazines.

Credit: Denver Police

RELATED: Man accused of shooting Denver woman while she was walking dog faces 22 charges

Close faces charges for two counts of first-degree murder, two counts of attempted first-degree murder, two counts of first-degree assault, nine counts of using a prohibited high-capacity magazine during a crime, two counts of prohibited use of a firearm and one count of disorderly conduct.

He also faces four sentence enhancers for violent crime.

According to Colorado Bureau of Investigation (CBI) records, Close had no prior criminal history in the state. 

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