A Louisiana college student desperately tried to fend off her killer by spraying him with mace and even stabbing him several times with his own knife before he fatally shot her, according to details revealed Friday in a guilty plea hearing.

Brandon Scott Lavergne, 33, pleaded guilty Friday to two counts of first-degree murder in the death of the student, Michaela "Mickey" Shunick, and the separate July 1999 slaying of Lisa Marie Pate.

Under a plea deal to avoid the death penalty, he was required to give details about both slayings in exchange for a life sentence without parole.

Shunick, a student at the University of Louisiana-Lafayette, went missing in the early hours of May 19 after leaving a friend's house on her bicycle. Surveillance videos captured Lavergne following her in a white Chevrolet Z71 pickup truck, changing lanes and turning corners in order to follow her.

Court documents say Lavergne, a registered sex offender, hit Shunick's bike with his truck, throwing her to the ground. Then, Lavergne either forced or persuaded Shunick to get into the vehicle and her damaged bike was loaded into the bed of the truck.

Shunick tried to use her cellphone to call for help but Lavergne, who had a knife and a semiautomatic handgun in his vehicle, threatened to stab her if she continued. Shunick sprayed mace in Lavergne's face and managed to wrestle the knife from Lavergne and stab him several times before he grabbed the knife from her.

Lavergne stabbed Shunick at least four times before she collapsed. He then drove 30 to 40 minutes to an isolated sugar cane field in north Acadia Parish.

"The Defendant believed that Mickey was dead from the stab wounds he had inflicted upon her. The Defendant drove deep into the sugar cane field and brought the Z71 to a stop, intending to drag Mickey's body into the field," the court documents said.

Shunick suddenly jumped up and stabbed Lavergne in the chest after re-arming herself with the knife. Lavergne then pulled his semiautomatic weapon and shot Shunick in the head. She died instantly.

With fresh wounds, Lavergne drove back to his home in Swords while Shunick's body slumped in the passenger seat. He destroyed his clothing, attempted to clean out his truck and got rid of the empty bullet casing. He then drove to an old cemetery in Evangeline Parish and, unable to dig a grave because of his injuries, covered Shunick under tree branches and debris.

Later, Lavergne dumped Shunick's bicycle under a bridge in Whiskey Bay and drove to New Orleans to stay with a friend, where he checked into a hospital, seeking treatment for his injuries.

A day later, Lavergne returned to the cemetery to bury Shunick's body.

Lavergne was arrested July 5 on charges of first degree murder and aggravated kidnapping. Shunick's body was eventually found Aug. 7. The body was in such an advanced stage of decomposition the coroner's office had to send it to forensic experts at Louisiana State University.

Lavergne was the "credible witness" officials say led them to the remains. Prison records show he was checked out of prison hours before her body was discovered.

The Advocate reports Shunick's sister, Charlene "Charlie" Shunick, said in a written statement that, "my sister, Mickey Shunick, was a warrior. If it wasn't for her, our community never would have been able to bring down a dangerous man that harmed multiple people."

Clay Lejeune, one of Lavergne's defense attorneys, says his client is relieved he can bring an end to the Shunick family's suffering.

"I think he had been carrying this. He was very remorseful throughout the process and wanted to bring some closure to the Shunick family. He wanted to give them some closure and recognized that a trial would only serve to create greater harm to them," Lejeune said.

Lavergne also pleaded guilty to the murder of Pate, whose body was found in Acadia Parish in 1999. Court documents say Lavergne and Pate checked into a hotel for several days shortly after they first met in Lafayette. Pate eventually told Lavergne she wanted to leave and see her children but Lavergne refused to give her a ride or let her borrow his vehicle to return home.

Court documents say Pate attempted to surreptitiously grab Lavergne's keys and wallet while he was asleep, but Lavergne caught her and bloodied her face and nose. Pate died a little later and fellow inmates of Lavergne have said Lavergne confessed to suffocating a woman with a plastic bag over her head.

Lavergne later moved Pate's body to Acadia Parish, where remnants of a plastic bag were found around the body's skull.