A former Georgia professor charged with fatally shooting an 18-year-old female college student last year for reasons that are still unclear has been sentenced to life in prison, prosecutors said.

Richard Sigman, 49, pleaded guilty on Monday to malice murder, three counts of aggravated assault, and three counts of possession in the death of Anna Jones, a student at the University of West Georgia, where Sigman taught at the time of the shooting.

The summertime shooting took place in Carrollton about 45 miles southwest of Atlanta. Sigman and Jones did not know each other, Carrollton Police Department Sgt. Meredith Hoyle Browning previously told USA TODAY.

Jones, who lived in Carrollton, was killed July 30, 2022 when Sigman shot into a parked car she was a passenger in, authorities said.

Bay Area:THC-infused candy at elementary school Halloween event leaves one child sick

Life in prison plus 55 years

Following a negotiated plea, attorneys in the case confirmed, Coweta County Judicial Circuit Superior Court Judge Dustin Hightower sentenced Sigman to life in prison with the possibility of parole.

Under Georgia law, Sigman must serve at least thirty years in prison before he is eligible for parole.

According to her obituary, Jones was a 2022 graduate of Mt. Zion High School and was "a cheerleader, soccer, and track star."

"Words cannot explain how much pain we feel," the victim's father, Carl Jones, wrote in a letter obtained by USA TODAY that he read to the judge before hs sentenced Sigman. "He took her hopes of college life and becoming an adult. He took her hopes of becoming a nurse and helping people and serving this community. He took her hope of becoming a wife and a mother. He took our hopes for what we knew Anna would become, and what she would accomplish."

USMC top officer hospitalized:Marine Corps Commandant Eric Smith hospitalized after apparent heart attack

Sigman was intoxicated the night of the shooting: DA's office

On the night of the killing, Sigman was intoxicated in downtown Carrollton while in the possession of a handgun, the Coweta County District Attorney's Office wrote in a press release.

Shortly after midnight, the release says, Sigman, also from Carrollton, stumbled into the lower level of the city courthouse's parking deck, pulled out the firearm and walked up to the parked vehicle occupied by the three women − all college students.

The release says Sigman approached the passenger side of the vehicle and banged on a window while "brandishing his gun."

Terrified, the victims attempted to flee and one of them began to back out of the parking space, the release continues. As they reversed out of the parking space, Sigman fired three shots − one which struck Jones in the head as she sat in the front seat passenger.

Jones was driven by friends to a hospital where authorities said she was pronounced dead.

No one else was injured, police said.

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at [email protected] and follow her on X @nataliealund.