A judge has rejected a plea deal for a teenager accused of sexually abusing a mentally disabled woman in suburban Des Moines.

The Des Moines Register reports (http://dmreg.co/2k6Bobk ) Judge Robert Blink said Wednesday that the deal wasn't constitutional because it wasn't clear Nicholas Fifield was fully advised of his legal options. The judge set an April 24 trial date.

A criminal complaint says Fifield, then a 17-year-old West Des Moines high school student, met the 18-year-old woman online and took her on a date in December 2015. The complaint says they went to his house and had sex, even though the woman said "no" several times.

He entered an Alford plea to misdemeanor assault, meaning he maintained his innocence but acknowledged prosecutors had enough evidence to convict him.