RACINE, Wis. (AP) -

A Racine student accused of molesting at least six young children and producing a cache of child pornography has pleaded not guilty to 49 felony charges.

Alexander R. Richter, 29, entered his plea Wednesday after waiving his preliminary hearing.

Prosecutors say Richter volunteered to babysit his classmates' pre-teen children and then repeatedly had sex with the boys and girls on camera as they cried and begged him to stop. The youngest alleged victim was a 4-year-old girl.

Charges include possession of child porn and first-degree sexual assault of a child under 13.

Investigators say they've identified six children in videos and photographs recovered from Richter's home. They say they believe there are additional victims, but aren't saying how many.

A message left with Richter's defense attorney wasn't immediately returned.