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COLORADO SPRINGS, COLO. -- Prosecutors in the case for the former wrestling coach accused of sexually assaulting boys on the team rested their case Wednesday, the fourteenth day of the trial.

Jim Tanner was the last witness to take the stand against Joshua Carrier. Tanner trains police officers on how to deal with sex offenders and also works with sex offenders after they've been convicted. He was considered a "blind witness" because he had no knowledge of the Carrier case.

Tanner has been declared an expert on subjects like this four times before Wednesday. The judge allowing Tanner to be considered an expert for a fifth time in this trial. Tanner said sex offenders generally try to gain access, draw victims toward them and create an alibi. In the Carrier case, the alleged victims said the then-Horace Mann Middle School assistant wrestling coach performed "skin checks" (exams to look for injuries) on them, and felt their genitals while doing so.

Tanner also said adults involved may be "groomed" by the suspect to believe nothing is wrong. In the Carrier trial, the security guard during the 2010-2011 school year accusations, Nick Graham, was the one who called the boys out of class and was present during some of the nude checks.

Many of the 22 boys who testified over the past three weeks said they trusted Carrier, saying he was a "nice guy" and "someone they could talk to." Tanner said it's common for sex offenders to use charm to groom potential victims.

"Becoming a sex offender takes years in the making," Tanner said. "Someone doesn't just wake up one day and decide to molest children."

Tanner also said at times, if the "grooming" process worked, a victim won't even know he or she has been assaulted. According to the boys' testimonies, many did not think anything was wrong until after Carrier was arrested in May 2011, months after the alleged assaults took place.

Carrier is accused of more than 200 criminal charges stemming from the alleged sexual assaults. He was the school's resource officer in 2009-2010 and is also a former Colorado Springs Police officer.

If convicted, he could face life in prison.

Thursday will be a motions hearing day, and the trial will resume Friday with Carrier's attorneys beginning their defense.