Baltimore County Police spokesperson Elise Armacost updates the Amber Alert situation involving missing 11-year-old Caitlyn Marie Virts. (Amy Davis/Baltimore Sun video)

Police believe the father of an 11-year-old girl abducted her from the Dundalk home where her mother was found dead Thursday morning. On Friday police had obtained an arrest warrant for 38-year-old Timothy Howard Virts in connection with the death of Bobbie Jo Cortez.

The Amber Alert issued Thursday for their daughter, Caitlyn Marie Virts, remains active on billboards throughout the region and told motorists to be on the lookout for a black SUV. Investigators believe the girl is with her father.

Baltimore County police said Friday they have reached out to other local and federal law enforcement agencies for assistance in the investigation.

"He is not supposed to have her, and we are concerned for her safety," police spokeswoman Elise Armacost said. She did not say why authorities are concerned.

The girl's mother, Bobbie Jo Cortez, 36, was found dead shortly after 9 a.m. in what police said was a violent scene at their home in the 3100 block of Ardee Way. Police said the death is being investigated as a homicide and said on Friday Cortez was observed to have multiple cut wounds to her upper body. An autopsy is scheduled for Friday to determine the cause of death, police said.

Police said Virts is a suspect in the abduction and investigators "want to talk to him" about Cortez's death.

The parents had separated and Cortez married another man, police said, but Virts had been staying at the home in recent weeks. Three children also lived there, including Caitlyn's twin sister and another boy, police said.

Caitlyn is 5 feet tall, weighs 80 pounds and might be wearing glasses, police said. Timothy Virts is 6-foot-3 and weighs 280 pounds. Both are white.

Police are looking for a black 1999 Dodge Durango with Maryland tag No. 5AJ4458. The vehicle is registered to 38-year-old Daniel Williams Cortez, who is married to Bobbie Jo and has been in jail since December on sex offense charges.

Daniel Cortez was convicted in 2009 of a fourth-degree sex offense, according to state records, and is on the state's sex offender registry. He was indicted again Wednesday on additional sex offense charges.

"Our detectives do not believe at this time that Cortez's criminal history is related to this homicide," Armacost told The Baltimore Sun.

An attorney for Cortez could not be reached for comment.

Timothy Virts' father said he learned that his granddaughter was missing when he saw the Amber Alert, which was issued at 10:45 a.m.

Peter Virts, 63, said he called Bobbie Jo Cortez's phone to find out what was going on, but his grandson answered.

"Pop pop, I can't talk right now," the boy said, and handed the phone to a detective, according to Virts.

Cortez was already dead. Virts said the boy "knew, but he couldn't say."

Peter Virts, speaking outside his East Baltimore rowhome, said he had no idea where his son might have taken the girl. He urged him to call and let him go pick her up.

He described Caitlyn as a "daddy's girl."

"I just want him to bring the baby home," he said.

A police cruiser sat in the driveway of the gray one-story house on Ardee Way late Thursday. A tire swing rotated in the wind in the front yard, a dented children's lacrosse stick lay in the snow, and there was considerable damage to the slats in the closed blinds in several of the windows.