Two brothers who raped a Grade 11 student for eight hours have led a "sad life" and "didn't stand a chance," according to their lawyers, who on Thursday addressed how much time each man should spend in prison for kidnapping and sexual assault.

"They didn't stand a chance from the minute they were born," said Cody Manyshots' lawyer, Alain Hepner, who proposed a nine-year sentence for his client.

The sentencing hearing continued Thursday for Corey Manyshots, 28, and Cody Manyshots, 24, who kidnapped and raped a 17-year-old girl.

Further tests done by forensic psychologists did not make available a defence of NCR (Not Criminally Responsible) despite the fact that both brothers have severe FASD (fetal alcohol spectrum disorder),

Corey, who has an IQ of 45 and can barely read or write, functions at the level of a six-year-old child, said his lawyer, Mitch Stephensen, who proposed a prison term of six-and-a-half years.

This case has been described as "horrific" by the prosecution. It has been delayed several times over the past year as reports were prepared on the severeness of FASD (Fetal Alcohol Spectrum Disorder) suffered by the brothers, their psychiatric states and their Aboriginal upbringing.

There are serious concerns both will reoffend when they're released, and the public has "reason to be concerned," said prosecutor Jonathan Hak. He described the brothers' actions as "predatory behaviour" when they kidnapped their victim.

In November 2014, the brothers grabbed their victim from a transit stop in Taradale, where she'd been waiting for a bus after watching a movie with a friend. For the next eight hours, she suffered repeated physical and sexual assaults — first in an alley near the bus stop and then at the brothers' nearby home.

The brothers' father and a friend were at the house, as well as Corey's baby and the child's mother. The sexual assaults continued overnight in different rooms of the home.

The girl was able to escape in the morning while they were sleeping.

The Manyshots pleaded guilty last year to kidnapping, uttering threats, sexual assault and robbery, but their sentencing hearing was derailed when lawyers realized how severely impaired both brothers are by FASD. Further testing was ordered ahead of Thursday's sentencing hearing continuation.

Crown seeking 12-year sentence

Last year, at the beginning of the sentencing hearing, the Crown said it was seeking 12 years for both brothers, who have criminal histories.

Both brothers are a high risk of committing violent, sexual crimes once they're released, noted Hak, who has asked provincial court Judge Terry Semenuk to order the brothers to serve at least half their sentences before they're eligible for parole.

Cody will get three years and nine months credit for the time he's already served, while about four-and-a-half years will be subtracted from Corey's sentence.

Stephensen has proposed a three-year probationary period for Corey, who he recommended attend a residential treatment program for people with mental illness and substance abuse in Ponoka, following his release from prison.

Semenuk has reserved his decision until January.