(CNN) -- The investigation of a Vermont girl's disappearance has led to charges against her stepfather in a separate case, authorities said Tuesday.
The arrest of Ray Gagnon, 40, is a "byproduct" of the search for 12-year-old Brooke Bennett, said Col. James Baker, director of the Vermont State Police.
Baker said Gagnon is suspected of sexually assaulting another child in 2007. He would not provide details.
Federal agents are preparing to also charge Gagnon, of San Antonio, with obstruction of justice for destroying evidence in the Brooke Bennett investigation, FBI Special Agent John Pikus said. Watch authorities report progress in the search »
Gagnon "has family members in this area, and he has been in Vermont on a regular basis," Baker said.
Brooke disappeared Wednesday, after visiting a convenience store in Randolph, Vermont, investigators said. Watch CNN's Nancy Grace speak to the missing girl's father »
A few days later, police said they found articles of clothing that they believe belonged to her.
She was communicating with someone on a social-networking Web site before she disappeared, said investigators, who have been examining a computer she used.
"This case is about social networking on the Internet," Baker said. "We're using every resource we can to tighten this up so we can find Brooke and bring her home."
Police said Gagnon's arrest stemmed from the investigation of the missing girl's uncle, Michael Jacques, 42, who has been charged for his alleged role in a sex ring known as "Breckenridge," CNN affiliate WPTZ reported. The charge against Jacques, a registered sex offender in Vermont, does not involve his niece.
Jacques' alleged victim told police that her first contact with "Breckenridge" occurred when she found a note under her pillow saying that she had been chosen to participate in a "program for sex," according to an affidavit cited by WPTZ.
The affidavit says she met three men from the program, including Jacques, who was supposed to be her "trainer." The alleged victim said she met three girls who were also in the program," WPTZ reported.
Authorities began focusing on Jacques based on information they gleaned through computer forensics, Baker said, though he refused to comment on the family dynamics between Brooke and her uncle.