SOMERSWORTH, N.H. – A 19-year-old man accused of slashing his girlfriend to death and dumping her body in Maine before fleeing to Massachusetts was charged Tuesday with second-degree murder.

Anthony O’Leary of Som-ersworth told police he got into a fight with Treasure Genaw, 17, of Berwick, Maine, while driving from Berwick to Somersworth on Monday night. He said she was 12 weeks pregnant.

O’Leary told police he stabbed his girlfriend in the eye, throat and stomach, a state police affidavit said.

Afterward he drove back to Maine, threw away the knife and left the body on a dirt road in South Berwick, the document said. He was arrested after a chase in Massachusetts and returned to New Hampshire on Tuesday.

Authorities could not confirm that Genaw was pregnant but said an autopsy was being performed.

The girl’s father, Bradley Genaw, told WMUR-TV his daughter had broken up with O’Leary recently, and that O’Leary “couldn’t take no for an answer.”

He described O’Leary as evil and possessive.

Days away from her high school graduation, Genaw wrote in her yearbook, “Special thanks to my parents, my sister and best friend – Liz, and Tony, my soul mate.”

O’Leary was arrested Monday night in Massachusetts, after state police tried to stop his speeding car southbound on Interstate 95. They chased him, and he left the highway at Route 113 in Newburyport and stopped. Troopers said they found cuts on his hands and what appeared to be blood in the car.

Investigators determined the car O’Leary was driving was registered to Genaw’s father in Berwick and that the girl was missing.

Information provided by O’Leary in Massachusetts led police to her body along Route 236 in South Berwick, according to investigators.

O’Leary was arraigned Tuesday in Newburyport District Court on vehicle violation charges. He agreed to be arraigned on a murder charge Wednesday in Dover District Court. He was being held without bail in Newburyport.

Genaw, who would have turned 18 on June 18, was to have graduated from Noble High School in Berwick on Saturday. She attended a rehearsal on Monday morning. On the folding chair with her name taped to it was a basket of daisies, carnations and chrysanthemums. Students were putting together a scrapbook to give her family.

“She was always willing to give of herself,” said Christian Elkington, high school principal. “She always had a positive word to say.”

Elkington said Genaw, a certified nursing assistant who aspired to be a nurse, did a senior project on Alzheimer’s disease, and it got the highest possible mark. She presented it at the end of May.

Genaw was working two jobs while attending school, one at a home for the elderly in Portsmouth, the other at a Dunkin’ Donuts in South Berwick.

“She hated people who wasted their potential,” Elkington said.

Genaw and her family were founding members of the Family Christian Church in Berwick, said the Rev. Al Robbins, pastor.

Robbins, who has known Genaw for 12 years, said she was a member of the teen choir and had gone on a mission trip to South America with the church.

“She had a heart for kids all over the world,” he said.

Associated Press reporter Sara Leitch in Berwick, Maine, contributed to this story.