WHEAT RIDGE, Colo. -- A Wheat Ridge middle school science teacher goes to trial next week to face charges of sex crimes involving some of his students.

Marshall Walker, 33, has taught at Everitt Middle School since 1998. He is charged with 55 counts of sexual exploitation of a child, enticement of a child, and sexual assault of a child.

The charges stem from alleged incidents several years ago. Walker allegedly took pornographic pictures of his students after promising them gifts and promising to change a failing test grade, prosecutors said.

Pornographic pictures of the three known children were found in Walker's home, but three other children seen in the pictures have not been identified, the district attorney said.

One of the victims was 13 years old during the 2002-2003 school year when he was one of Walker's eighth-grade students. The teen told investigators that he went with Walker on a skeet-shooting trip and when he arrived at his teacher's home, he noticed that there were pornographic DVDs on his table.

When they returned from the trip, the suspect allegedly asked the boy if he could take pictures of him naked, in exchange for a duck call, food from Taco Bell, and a deck of cards with naked women on them. When the teen refused, the suspect allegedly offered to change the teen's failing grade on a test he had just taken. The teen agreed.

The boy later told authorities about the incident, and in May 2006, police conducted search warrants on Walker's former home in Lakewood and current home in Thornton.

Officers found 44 Polaroid pictures of boys ranging from 8 to 14 years old and two homemade videos of boys masturbating, the district attorney said.

Two of the boys in the pictures were Walker's students at Everitt and one boy was his student when he taught at Bell Middle School.

Walker has taught science classes, coached boy's basketball and participated in hunting and fishing activities.

Copyright 2007 by TheDenverChannel.com.