HONOLULU -- One of the most-used strategies against sexual predators is under attack in state court.

A jury is being asked to decide if undercover officers unfairly trapped a man charged with Internet enticement of a child.

So far, most of the men accused of being Internet predators in Hawaii were not caught with children. Instead, they were caught in undercover stings in which agents pose as minors.

A case that began Wednesday could test that technique.

Ernest Roberts, 47, spent months online with undercover police who claimed to be a young girl named Mariah Sato.

"In the first chat, Mariah tells Mr. Roberts she is 13 years old -- right off the bat," Deputy Attorney General Albert Cook said.

"Mr. Roberts was first of all entrapped. He was led into this situation that he would not have otherwise been in," defense attorney Don Wilkerson said.

The prosecutor quoted from sexual chats and phone calls in which he said Roberts seemed to know he was in illegal territory.

Roberts' attorney also pointed to the chats and said that despite the sexual nature, he didn’t know the girl was supposed to be underage.

"Many times he asked her, 'Who is this, who am I talking to, I don't know who I am talking to, I don't know who this is,'" Wilkerson said.

He said that the police do not have evidence of the sexual impropriety either.

"The only information that would indicate one way or another -- HPD just coincidentally doesn't have it," Wilkerson said.

Police said they arrested Roberts in his sport utility vehicle across the street from the Humane Society, where he was supposed to meet the girl. But his attorney said he never intended to cross the street.

"He never took that last step because he did not want to meet this girl," Wilkerson said.

The case could last another day or two and could influence both the tactics of the police and the people they arrest.