A 17-year-old Wisconsin boy is in custody after his mother and stepfather were found dead in their home during a welfare check last week.

A criminal complaint filed on Monday charges Nikita Casap with operating a motor vehicle without the owner’s consent and theft of movable property, WTMJ reported.

Donald Mayer and Tatiana Casap were found dead in their Village of Waukesha home Friday morning when family members requested a welfare check because they hadn’t heard from the family in about two weeks, as CrimeOnline reported. Police have still not confirmed the identities of the victims, and the boy, who was arrested in Kansas on Friday night, has not been charged in their deaths.

The Waukesha County Sheriff’s Deparment initially said one person was found dead and other family members were missing, then corrected that to two fatalities the following day. They added that a “person of interest” was in custody, but no information about that came until the criminal complaint was filed on Monday.

According to the complaint, Nikita Casap was driving his father’s car when he was arrested in WaKeeney, Kansas. The complaint said that a neighbor saw the boy driving the vehicle on February 23 and that he left Wisconsin the next day, with GPS data showing him traveling through Iowa, Nebraska, Wyoming, and Colorado.

Investigators initially said they found Mayer, Tatiana Casap, and the family dog dead inside the home, but the complaint said a small black dog was seen in the vehicle both before the boy left Wisconsin and in Iowa, and the dog was still in the car when police stopped him after he ran a stop sign in Kansas.

Criminal Complaint Nikita Casap 67c6271f4c5d0 by kc wildmoon on Scribd

Investigators also found a firearm believed to belong to Mayer, ammunition, spent shell casings, and the victims’ drivers’ licenses in the vehicle, the complaint said.

The bodies of Mayer and Casap were found in different rooms of the home, both covered with blankets and clothing. Tatiana Casap had “a possible exit wound in the back near right shoulder,” the court documents said, while Mayer had “an obvious wound to the back of victim’s head.”

Tatiana Casap’s body was found when police initially made entry into the home, while Mayer’s body was found in an office while they were executing a search warrant.

According to WISN, the boy is still in Kansas awaiting extradition to Wisconsin, and the investigation is ongoing.