Todd Tackwell, 35, of Hastings, Neb., was arrested after the stop when police became suspicious of a 13-year-old passenger. After talking to the girl and her parents, the officer determined there had been inappropriate sexual behavior involving the pair, a Pleasanton police report said.
Tackwell admitted to police that the day before his arrest, he'd been notified of the indictment, following an investigation by Homeland Security into a child pornography distribution case dating to 2008, the report said.
Police say Tackwell met the 13-year-old through a chat room in October 2009 and continued the relationship by phone.
In January, he drove cross country to meet the girl and began "a seven-month extensive sexual molestation of the child" that ended with his arrest, the report said, which stated the girl's parents were not aware of Tackwell's contact with her.
Tackwell is being held in Santa Rita Jail on a charge of continuous sex abuse of a victim under the age of 14. He's set to enter a plea Sept. 9.
Police withheld the information from the arrest, which occurred July 24, because of what they describe as "the sensitive and complex nature of the investigation."
Anyone with information that could help in the investigation is asked to contact Pleasanton police at 931-5100.