Amber Alert - Man, 13yo Step-Daughter and Her 2 Week Old Baby Missing

Teen Mother and Infant Son Allegedly

Abducted by Stepfather After Police

Began Investigating Her Sexual Abuse

  video 0:37

BY CHRIS HARRIS

Illinois authorities tell PEOPLE they cannot say with any certainty who fathered the infant delivered two weeks ago by a 13-year-old girl who has been missing since Sunday, when police allege her 39-year-old stepfather kidnapped her. 

But "once we are able to find out the paternity of the child, there will no doubt be charges of criminal sexual abuse filed against that individual," says Greenville, Illinois, Police Chief Lou Lorton.

Police are still searching for Christopher Derleth, who they say vanished along with his stepdaughter, Katherine Derleth, and the girl's infant child, who is also named Christopher.

According to police, Christopher's van was spotted just south of Charleston, West Virginia, late Sunday, and an AMBER Alert was issued. But the three haven't been seen since. 

Investigators have filed charges against Christopher for violating a protective order barring him from having contact with Katherine, and officials indicate they plan to add kidnapping and child abduction charges. 

Police are not discussing what prompted the alleged kidnapping but have said they believe the abduction was planned.

Christopher Derleth

Chief Lorton says his officers began investigating the specific circumstances surrounding Katherine's pregnancy months ago.

As a result of that probe, which focused on her stepfather as well as another man she had been living with, the state removed Katherine and her son from her home and placed them with a foster family, Lorton says.

A protective order was also issued, barring Christopher from contact with the teen, according to authorities.

"The original complaint stemmed from the fact that there was a 13-year-old that was pregnant and there were, at the time, two individuals living with her in the home," Lorton tells PEOPLE. "We obviously don't know who the father of the child is, but that's what launched the investigation."

According to Lorton, detectives were working to determine the child's paternity before Katherine and her son were abducted.

"We are still investigating, and we are fairly certain Katherine and her stepfather are out there," Lorton says.

The state had also looked into a 2015 complaint involving Katherine but had insufficient evidence to continue with a full-scale investigation, authorities said.

Katherine Derleth

Despite repeated calls, PEOPLE has not been able to reach Derleth relatives for comment.

Katherine's mother, Jennifer, told KSDK she is praying for her daugher. She said the teen loves cooking, drawing and music.

Jennifer declined to discuss Christopher's alleged kidnapping, citing legal reasons, according to the station.

"To Katherine, if you're listening to this, know that your sister and your family all love you very much," Jennifer said. "Stay strong, we're praying for you and have faith that you'll be in my arms again."

Let us join her in that prayer.

Police are asking that anyone who sees Katherine, her baby or Christopher immediately call 911.

Minnesota Man Jailed in Death of Co-worker's 5-Year-Old Girl

Zachary Anderson and his victim Alayna Ertl

LITCHFIELD, Minn. (AP) — A Minnesota man remained jailed Sunday on suspicion of first-degree murder and kidnapping in the death of a co-worker's 5-year-old daughter while investigators worked to determine what happened.

Zachary Todd Anderson, 26, of Monticello, was being held in the Crow Wing County Jail in the death of Alayna Ertl, whose mother discovered her missing from her home in the central Minnesota town of Watkins about 8 a.m. Saturday. She was last seen about 2 a.m. when she was put to bed.

Also missing was a pickup truck belonging to the girl's father, Matt Ertl, whose cellphone was still in the truck. It was pinged at 9 a.m. in Todd County before it was turned off, authorities said.

Alayna's disappearance led authorities to issue an Amber Alert. Her body was found nine hours later in a wooded area near Motley in Cass County, about 80 miles to the north. Authorities arrested Anderson and found the missing truck in the same county.

"Our suspect in this case is a family friend, co-worker of the victim's father, and was staying the night up in Watkins last night," Meeker County Sheriff Brian Cruze said Saturday night. "He had previously been to that residence and spent a night here and there — so he's not a stranger and not new to the residence, but was just there for the night."

Investigators have not disclosed how the girl died. Autopsy results were pending. Online court records available Saturday listed only minor traffic violations for Anderson, and it wasn't immediately clear if he had a lawyer who could comment on his behalf. He was not immediately charged.

"We have no known predatory sexual offender information on him or anything like that," Cruze said. "We have no known motive. We are at a loss as to why this happened at this time."

On Sunday, the sheriff's office was referring reporters to the state Bureau of Criminal Apprehension, which had no immediate updates on the investigation.

The sheriff said Alayna's death was a blow to investigators.

"Obviously not the outcome that we wanted and when we did learn the information, the officers in the room, you could see ... it weighed heavy on them," Cruze said. "We tried everything we could today to find her safely and obviously that didn't happen. And we know that it doesn't compare to what the family's going through right now, but we felt we did everything we possibly could."

    Watkins, MN