Former Saybrook master and geology professor Antonio Lasaga, convicted of child pornography and sexual assault charges, was taken into federal custody Thursday, more than three years after he was first arrested.

U.S. District Judge Alvin W. Thompson granted a prosecution motion to remand Lasaga to custody, citing recent behavior that indicated the 52-year-old Lasaga was a flight risk.

“His probation officers have been incredibly uncomfortable with him,” Thompson said. “There is a sense of unease.”

Lasaga’s freedom ended just 11 days before he is to be sentenced on federal child pornography charges and two weeks before his sentencing on state sexual assault charges. He faces more than 100 years in prison.

Assistant U.S. Attorney Kari Dooley said a recent psychological report suggested Lasaga was prone to impulsive behavior making him a flight risk. FBI agents kept surveillance on his Cheshire home overnight Wednesday, she said.

“When faced with the seriousness of his reality, he might act impulsively,” Dooley said.

Lasaga was arrested in 1998 when federal investigators, tipped off by a Yale graduate student, searched his on-campus apartment. They found hundreds of thousands of images of child pornography and homemade videotapes. He pleaded guilty in 2000 to federal child pornography charges but was allowed to remain under house arrest while legal challenges were resolved to continue with mental health counseling and to prepare for his sentencing.

Yale President Richard Levin fired Lasaga last year, and the former professor pleaded no contest Jan. 4 to state charges that he sexually assaulted a boy who appeared in some of his videos. Lasaga had served as the child’s mentor.

Lasaga continued to meet with colleagues, research, and publish as he fought his legal battles during his house arrest.

His attorney, Diane Polan, argued that he should remain free in part because he had several scientific papers to finish writing and editing. She said she also needed time with him to help prepare for sentencing and needed to say goodbye to his family, including his elderly mother who has Alzheimer’s disease.

“He is not acting like someone who has any intention of fleeing,” Polan told the judge. “There’s been no violations. He would have been in front of you in a heartbeat if there were.”

Federal sentencing is Jan. 28 and state sentencing is Feb. 1.

–Yale Daily News and The Associated Press