DENVER (CBS4) – On what would have been her 22nd birthday, the father and boyfriend of Isabella Thallas filed a lawsuit against her alleged killer and a former Denver police sergeant. Thallas and her boyfriend, Darian Simon, were shot while walking their dog outside of a Denver apartment complex on June 10, 2020.

Isabella Thallas

Isabella Thallas (credit: Thallas Family)

The lawsuit filed on Tuesday claims that former DPD Sgt. Daniel Politica failed to responsibly and securely store the AK-47 weapon used in the shooting. The Denver Police Department says the murder suspect, Michael Close, was a friend of the sergeant and took the firearm from the sergeant’s home without his knowledge or permission.

Michael Close (credit: Denver)

Simon was shot twice but survived. He told police the shooter yelled at them about the dog before he opened fire.

Darian Simon and Isabella Thallas (courtesy: Ana Thallas)

Upon learning his firearm was missing and that it may have been used in the homicide, DPD says Sgt. Politica notified investigators that the weapon belonged to him. The lawsuit claims Politica reported the weapon stolen 10-12 days after the shooting. The firearm was not issued by the Denver Police Department.

The lawsuit claims Politica owns Tyrant Arms, LLC, a gun shop in Arvada. It also claims Politica became concerned about Close’s mental health and was going to take him to a mental health facility on June 10, the day of the shooting.

Craig Silverman and Joshua Maximon, the attorneys representing Darian Simon and Isabella’s father, issued the following statement on Tuesday to CBS4:

“Today is the 22nd birthday of Isabella Joy Thallas. Bella and her beloved boyfriend Darian Simon should be celebrating. But Bella was murdered, and Darian Simon nearly murdered almost one year ago. The murder weapon was an AK-47 reportedly owned by DPD Sgt. Dan Politica.

“Politica was the owner/operator of Tyrant Arms, LLC. The murderer was Politica’s friend and confidante who somehow obtained the illegal (in Denver) assault weapon and prohibited (in Colorado) large capacity magazines filled with ammunition.

“Our lawsuit seeks answers and accountability. Honor Bella. Honor Darian. We intend to prove what really happened on June 10, 2020 in Denver, Colorado.”

Sgt. Politica resigned from the Denver Police Department on March 13, 2021. The department did not say if the resignation was related to the murder investigation. The resignation letter was dated February 13, 2021.

Sgt. Politica’s regisnation letter (credit: Denver Police Department)

In March, Michael Close pleaded not guilty by reason of insanity. The 36-year-old faces 22 counts, including first-degree murder, prohibited use of a large-capacity magazine, prohibited use of a weapon, and crime of violence.

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Audra Streetman