A New London judge ruled last week that a 20-year-old Baltic man was suffering from a mental disease or defect when he sexually assaulted a young girl in 2011.

Arthur J. Elliot, who has been incarcerated since state police charged him in October 2011 with first-degree sexual assault and risk of injury to a minor, has been transferred from a state prison to the Whiting Forensic Institute, a state psychiatric hospital for criminals.

Judge Susan B. Handy will sentence him June 5 after hearing from clinicians who are evaluating Elliot at Whiting.

Elliot was charged with sexually assaulting a 6-year-old girl he knew in August 2011. The victim’s mother told investigators the girl disclosed the incidents even though Elliot had warned her “not to tell her mother and he would not tell his.” In an interview with detectives, Elliott said the girl had “seemed curious” and had initiated the sexual contact.

Elliot’s attorney, Kevin C. Barrs, sought the insanity defense based on Elliot’s lifelong history of mental problems. Prosecutor Theresa Anne Ferryman did not oppose the defense.

Elliot has been diagnosed with cognitive disorder, psychosis, attention deficifit hyperactivity disorder, bipolar disorder, post traumatic stress disorder and mild mental retardation, according to a report in his court file. He also suffered from a tramautic brain injury as a child.

Dr. Marshall Gladstone, a West Hartford neuropsychologist, evaluated Elliot and determined he is not a good candidate for a standard adult sexual offender program.

“His limited level of maturity and intelligence suggests he would be largely unable to comprehend and integrate the program material,” Gladstone wrote.

- Karen Florin