A Wisconsin man, aged 38, is facing serious allegations after reportedly committing a series of heinous acts involving his pregnant girlfriend and her pet dog. Authorities claim Matthew R. Sierra murdered 27-year-old Alexis Pickett and her dog before setting her house ablaze.

Sierra has been charged with first-degree intentional homicide, both for Pickett and her unborn child, along with arson and animal mistreatment resulting in death. The tragic sequence of events unfolded at Pickett’s residence on Taylor Street in La Crosse, where the local fire department responded to a fire call at approximately 3:30 a.m. on November 13. Upon arrival, firefighters were met with dense smoke and tragically discovered Pickett deceased inside the home.

According to a criminal complaint accessed by Law&Crime, an autopsy revealed crucial details: Pickett’s lungs lacked soot, and her carbon monoxide levels were low, indicating she had died prior to the fire. The exact cause of her death remains undisclosed. Investigators also found her dog, which had been killed before the fire, under a toilet, as noted in the affidavit.

Surveillance footage has shed light on Sierra’s movements that night. It captured him arriving at Pickett’s home around 12:45 a.m. and departing roughly two hours later. Notably, smoke alarms were activated as he entered his vehicle.

The relationship between Sierra and Pickett was complex, marked by their shared responsibility for a child and Pickett’s pregnancy with their second. Allegedly, Sierra pressured Pickett to terminate the pregnancy, threatening to pursue custody of their first child if she resisted.

Sierra and Pickett already had a child together and she was pregnant with their second child. But he wanted her to have an abortion and threatened to seek custody of their first child if she refused, cops alleged.

Detectives spoke with Pickett’s friend, who said, “All I know is that they have been on and off and they have been constantly fighting because he found out she was pregnant with his kid and he didn’t want anything to do with it.”

The defendant claimed he was at a gas station at the time of the fire, but cellphone data showed he was at Pickett’s home.

Cops arrested Sierra on Tuesday and took him to the La Crosse County Jail, where he remains on a $1 million bond. His next court date is set for Dec. 23.

“This has been a very diligent, comprehensive, and strategic investigation in collaboration with the La Crosse Fire Department and the Wisconsin Department of Justice Division of Criminal Investigation and the Wisconsin State Fire Marshal’s Office,” City of La Crosse Police Chief Shawn Kudron said in a statement. “Our thoughts continue to be with the Pickett family.”

Sierra is a mechanical design professor at Western Technical College, according to local ABC affiliate WXOW. He was placed on administrative leave.