BAYTOWN, Texas -- Police have detained a man described as a person of interest after a mother and her 13-year-old daughter were slain in their Houston-area home, and an older daughter was missing.

Cynthia Morris, left, and her daughter Breanna Pavilicek, 13

Baytown police Lt. Steve Dorris said officers questioned the 21-year-old man Wednesday.

Police on Tuesday, responding to a relative not being able to contact family members, found the bodies of 37-year-old Cynthia Morris and her daughter, Breanna Pavilicek. Both were shot.

An Amber Alert was issued for 16-year-old Kirsten Fritch, who also lives at the home.

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Officers in Texas City overnight detained a Baytown man who CBS affiliate KHOU reports is Kirsten Fritch’s boyfriend. He was reportedly being held on a resisting arrest charge that stemmed from an encounter with Texas City police on Tuesday night. No charges have been filed in connection with the deaths.

Police were seen searching near a Texas city bar on Thursday.

Fritch’s grandmother, Barbara DeRamus, told the station the man started dating Fritch after they met online and that he moved into the family’s house, according to DeRamus. She says Fritch’s mother wanted him out.

“This is a mother and a grandmother’s worst nightmare,” DeRamus told the station. “...I don’t think I’ll ever get over this.”

Lt. Dorris says the mother’s car was missing, but was recovered when the man was located. Baytown police tell KHOU they believe the man knows where Fritch is, but isn’t cooperating with investigators.

Police fear Fritch could be in danger and are urging anyone with information to contact Baytown Crime Stoppers at (281) 427-8477 or the Baytown Police Department at (281)422-8371.