FORT COLLINS, Colo. -- Fort Collins police say there could be more victims in the case of a chess teacher who's accused of sexual assault.

Robert Snyder was arrested Tuesday for allegedly engaging in inappropriate touching and behavior with two of his students in the past year. Police said the two alleged victims are boys between the ages of 11 and 13.

Wednesday, a judge refused to lower Snyder's $750,000 bond in the case.

Police said that dozens of calls have come in regarding Snyder, many from parents concerned about the charges against him. The police investigation was called "lengthy" by investigators.

Snyder owns the Fort Collins-based Chess for Juniors, which operates out of his home. Its Web site lists it as "one of the nation's largest and most active private chess clubs for youth." Snyder is the owner and sole instructor.

He was jailed on two counts of sexual assault on a child by a person in a position of trust and two counts of sexual assault on a child -- pattern of abuse. The alleged assaults occurred at his home on Silver Creek Drive in Fort Collins, according to police.

The allegations aren't the first to surface regarding Snyder who moved to Colorado from California in 2000.

In 1983, he was found not guilty on four counts of sexual assault a California student. A judge dismissed the fifth count against him, according to the Los Angeles Times.

The charges were filed after the father of one of his students found Snyder and his son in the boy's room with a chair wedged against the shut door, the Times reported.

The not guilty verdicts came after a four-week trial and two hours of deliberation by the jury.

Snyder is the author of several chess books published by Random House, which includes the bestseller "Chess For Juniors," and has written articles for "Chess Life" and "School Mates" magazines, according to his Web site. The Web site also said that Snyder taught the game to students such as actor Will Smith, and the son of actor Nicholas Cage.

Snyder's lawyer said that his client is distressed about the charges and he expects Snyder to be vindicated.

Snyder's next court appearance is set for Sept. 22.