JACKSONVILLE, Fla. - A Jacksonville man is in police custody for the stabbing death of his girlfriend Sunday night.

57-year-old Thomas Webster is facing murder charges for allegedly using what police believe was a kitchen knife to stab his girlfriend in the back at their Mandarin home.

It happened in the 3800 block of Millpoint Drive. An exact time is unknown, but the Jacksonville Sheriff's Office believes it was within a two hour time frame of around 7 p.m.

The victim is 54-year-old Patricia Burner.

Lt. Rob Schoonover said she and Webster had been living together for three years, but that Burner was in the process of moving out and relocating.

He said it is unclear at this time if Webster was going with her.

He reportedly went to a nearby Kangaroo gas station on Old St. Augustine Road and told the clerk on duty to call 911.

JSO officers responded and received what Schoonover likens to a confession from Webster.

"When the police got there, he advised, he told the officers that he got in an argument with his girlfriend and apparently hurt her," he said.

That's when Schoonover said officers responded to their home and found Burner dead with a single stab wound to the back.

At first, Schoonover said Webster was being cooperative, but became more uncooperative before eventually demanding a lawyer.

Alcohol appears to be a factor.

Schoonover said Webster went to the same gas station earlier in the day to buy liquor.