Authorities in Minnesota said that what habitual violent criminal Christopher M. Strong Sr. did to his girlfriend — holding her captive for three days last year while he beat and repeatedly raped her, then pushing her in front a moving car — was "one of the most brutal" sexual assault cases that prosecutors have ever brought before a federal court.

It was time, they asserted, to acknowledge the "shocking reality" that the 36-year-old Strong is a "sadistic … rapist" who is "incapable of living a law-abiding life" and must be locked up for life.

Federal Judge Richard Kyle, however, rejected the argument for a life sentence and gave the resident of the Red Lake Indian Reservation a 30-year prison term, still far more than the 4½ years he was given for a similar offense he committed in 2009 against his ex-wife.

"Any woman who is romantically involved with the defendant is in grave danger," the prosecution argued in a court filing leading up to the sentence in Duluth. "The only way to protect the public from a career criminal like [Strong] is to keep him incarcerated for the rest of his life."

Strong's defense, in its pre-sentencing argument, sought a prison term of no more than 15 years. It noted that Strong had "a decent childhood," but the difficult atmosphere on the reservation led him to a life of substance abuse, suicide attempts and repeated criminal offenses.

According to the criminal complaint and other court documents:

On June 8, 2014, police and emergency medical personnel were called to Hwy. 1, just east of Red Lake, about a vehicle hitting a pedestrian. Moments later, a car passed by and was flashing its lights at the officers.

Police caught up with the passing vehicle at the Red Lake Hospital, where a woman was being treated for numerous wounds, including a broken lower left leg, where the bone was protruding. She also was bruised on her face, arms, torso and legs.

The woman said Strong pushed her in front of a car after she fled from three days of confinement and rape.

Over the three days, she told investigators, Strong bit her on the face, grabbed her by the hair, choked and punched her, and raped her at least five times.

Jurors in December convicted Strong for the attack, which occurred while he was on supervised release from the 2009 assault.

After serving his prison time for that earlier assault — less than half the 10 years he could have received — Strong cut off his electronic monitoring bracelet and resumed abusing drugs and alcohol.

Strong's criminal history includes several other instances of domestic abuse and threatening a police officer.