Sentencing is to resume in October for two brothers who randomly kidnapped a teenage girl and repeatedly sexually assaulted her.

Corey and Cody Manyshots pleaded guilty in October 2015 to kidnapping, uttering threats, sexual assault and robbery.

Sentencing arguments had already begun last year, but tests ordered for the brothers last December indicated both suffer the effects of severe fetal alcohol syndrome.

That led to discussions about whether the brothers are not criminally responsible on account of a mental disorder.

Psychiatric tests on the two men were conducted at the Southern Alberta Forensic Psychiatry Centre.

"The reports are done. They were appropriately returned to remand," Mitch Stevenson, who represents Corey Manyshots, said at a Thursday court appearance.

He said outside court that the findings of psychiatrists regarding criminal responsibility would be released when sentencing resumes Oct. 5.

Court has heard that the mother of the two men drank heavily during both pregnancies. Effects of fetal alcohol syndrome can include lifelong physical, mental and behavioural difficulties, as well as learning disabilities.

Grade 12 girl abducted in 2014

The pair approached the 17-year-old girl at a northeast Calgary bus stop in November 2014, forced her into an alley and sexually assaulted her.

The brothers, both in their 20s, then abducted the Grade 12 student and took her to their home, where they sexually assaulted her another 15 times until she was able to escape about eight hours later when they fell asleep.

In its original sentencing arguments, the Crown asked for 12-year jail terms for each of the men.

In June, lawyer Alain Hepner, who represents Cody Manyshots, told court he believed the two young men had "fallen between the cracks of life."

Hepner said if the two are found to be not criminally responsible, the public doesn't have to worry about them being set free.

"They're going to an institution either way," he said.

"It might be a psychiatric hospital. It might be a jail. That's what's going to happen. They're not getting out of jail. Not any time soon."