FORT COLLINS, Colo. -- A judge has ordered chess teacher and author Robert Snyder to stand trial on charges of sexually assaulting three students at his home, including one who may have been his stepson.

Robert Michael Snyder, 51, faces four counts of sexual assault on a child by a person in a position of trust plus two sentence-enhancing counts of sexual assault on a child pattern of abuse. After a hearing, District Court Judge David Williams bound the case over for trial.

Snyder has not entered a plea and a trial date has not been set.

Snyder, author of the "Chess for Juniors" book series is accused of incidents that allegedly happened at his home in late 2002 and summer of this past year. Snyder, through his attorneys, has denied wrongdoing.

Snyder is free on a $250,000 bond. His next hearing is March 9.

Fort Collins police officer Kim Cochran testified that two boys allege Snyder performed oral sex on them, while a third alleges Snyder put his hands down his pants.

Cochran said one incident that happened at the home between Sept. 7 and Nov. 15, 2002, involved an 11-year-old boy, whose mother was married to Snyder on Oct. 30, 2002. That marriage was annulled at Snyders' request, according to testimony.

Snyder's attorney Andy Gavaldon argued that the charges relating to his possible stepson and a 13-year-old should be dismissed because there wasn't enough evidence to support the charges.

Cochran testified that DNA tests conducted by the Colorado Bureau of Investigation could not conclusively determine whether it was Snyder's, but that Snyder was part of a very small group that could not be excluded.

Snyder is a former Western U.S. Chess Champion. According to his Web site, his students have won first place 36 times in championship sections at the National Scholastic chess competition.