RACINE — A Wisconsin college student is accused of molesting six young children and videotaping the assaults under such titles as “Monster Unleashed,” and police said Friday they think there are more victims.

Alexander R. Richter, who attended Gateway Technical College, was jailed on 49 felony charges after authorities say he volunteered to baby-sit his classmates’ children and then repeatedly had sex with the boys and girls on camera as they cried and begged him to stop. Police said they have identified six children in videos and photographs recovered from Richter’s home in Racine, about 30 miles south of Milwaukee.

Investigators are asking other victims or their families to come forward with information.

“We’re not putting a number on it, but from the evidence we’ve recovered we believe there are additional victims,” Racine police Sgt. Marty Pavilonis said.

Richter, 28, was arrested last week and faces dozens of charges including first-degree sexual assault of a child under 13, sexual exploitation of a child and possession of child pornography. He remained in jail Friday after a judge set his bond at $1.5 million in cash a day earlier.

Richter’s public defender, Margaret Johnson, did not immediately return a message for comment. A preliminary hearing has been set for Wednesday.

According to a criminal complaint, Richter approached at least one classmate last year and offered to baby-sit her children — a son who was then 6 years old and a daughter who had just turned 4. Richter is accused of making at least 11 videos of himself having sex with both children, including one in which police say he guided the boy into attempted sexual activity with his sister.