Officer Christine Saul of the Frederick, Md., police department testified that she was working undercover on Walnut Street on March 22 at 12:10 a.m. when a white pickup truck pulled over to the curb.
She testified she walked over to the truck and asked the driver what he was looking for. She said he replied - in street jargon - that he wanted a sex act.
"I asked him how much he had and he said $15," Saul said.
After the transaction was agreed upon, Saul said she walked away - a signal that uniformed police officers could come and arrest Henderson.
Under questioning by defense attorney Daniel Zanchettin, Saul denied that she pointed Henderson out in court Monday because he was the only black man in the courtroom.
"I recognized him as soon as I walked in the door," Saul said.
Henderson took the stand and admitted that he pulled over and talked with Saul that morning.
"I asked her if she was a cop - twice - and she asked how much money I had," Henderson said.
He said he never asked her for sex and when she told him to pull around the corner, he said "no thank you."
Assistant State's Attorney Joe Michael asked Henderson why he was in the area of Walnut Street - a known prostitution hot spot - at 12:10 a.m.
Henderson said he'd been drinking and he only pulled over to decide whether to go on driving.
He also insisted that he only asked Saul if she was a cop because he thought she looked familiar.
Henderson was the fifth man caught in that prostitution sting last March in Hagerstown to come to trial so far.
On May 29, four men were granted probation before judgment by Washington County District Judge R. Noel Spence after pleading guilty to one count each of solicitation.
Those men ranged in age from 26 to 76 and were fined between $100 and $400 and given 40 hours of community service to perform, court records said.
Also appearing before Wright Monday in connection with the March 22 sting was Carline Annette Bailey, who pleaded guilty to one count of fourth-degree sex offense.
Bailey, 40, formerly of Hagerstown, was given a one-year suspended jail sentence. She is currently living in a shelter in another county, court records said.