The teenager described his state of mind when a teacher at his Howard County high school allegedly pulled down the student's underwear after school one day last year and took photos of him nude.

"I was extremely shocked," the 18-year-old testified in Howard County Circuit Court yesterday. "I didn't know what to do. I was scared. I froze. I basically stopped thinking."

The student's account of the events of Jan. 8, 2007, came on the first day of testimony in the trial of Alan Meade Beier, 53, a former River Hill High School science teacher. Beier is charged with sex abuse of a minor and second-degree assault.

The accuser, who was 16 at the time of the alleged incident, told Judge Diane O. Leasure he went to school that day about 6 p.m. to help Beier set up lights and to model for photographs to earn community service credits required for membership in the National Honor Society.

The student said that after classes ended that day, Beier told him that photos taken for the Mr. River Hill High School pageant had come out fuzzy and he needed help redoing them. Beier, who did not have the student in class but was the sponsor of an after-school club to which the student belonged, asked him to come to school in the evening to assist with fixing the lights and to model in some pictures.

However when Beier began taking photos, he pulled the student's boxer shorts down to his ankles and told him to cover his genitals with a table tennis paddle, the accuser testified. Beier also told him to lie face-down on a table and pulled his boxers down again. Police later seized the photos, some of which show the teen's nude backside.

The teen said he went to a friend's home afterward and recounted the incident to two friends. He said that as he told his friends his account, he was "shaking" and his "body was trembling."

"I knew something was extremely wrong with what happened," he said.

Prosecutors plan to argue that Beier sexually exploited and assaulted the teen.

"He told [the accuser] that he will help him out with National Honor Society hours," assistant state's attorney Claude deVastey Jones said in her opening statement yesterday. "[The accuser] went there under that guise, believing a teacher, believing someone he thought he could trust."

Beier's attorney, Joshua R. Treem, argued that his client's actions do not constitute exploitation or assault under state law. He concedes that Beier took the photos, which were found by police on a mini-disc in a Sony camera in Beier's home and transferred to two computers the morning after the teen reported the incident. The teen testified that Beier assured him he would delete the photos.

"The focus really has to be on the acts of Mr. Beier to [the teen]," Treem said in his opening statement. "Sexual abuse has to be directed toward the minor. In fact, there was no act done to [the teen] that amounts to sexual exploitation under the statute."

Beier chose to have the case heard by the judge instead of a jury. Other witnesses who testified yesterday included school officials and the accuser's father, who described his son's demeanor when the boy told him about the incident that night.

"As we walked upstairs, he started crying," the father said.

Police also have charged Beier with fondling a 17-year-old female student and with sexual misconduct with a third student. Trial dates in those cases have not been scheduled.

The defense is expected to call witnesses today.

Beier is one of three Howard County teachers arrested during the 2006-2007 school year on charges of having inappropriate sexual contact with students.

tyeesha.dixon@baltsun.com