AMES, Iowa — The man who fatally stabbed a former Iowa State University golfer from Spain while she was playing a round near the school was sentenced Friday to life in prison without the possibility of parole.

Collin Richards pleaded guilty on June 14 to first-degree murder in the Sept. 17 slaying of 22-year-old Celia Barquin Arozamena. Police said Richards stabbed her on the course near the central Iowa campus in Ames and left her body in a pond.

Richards had been staying at a homeless encampment in nearby woods. Ames police reports show that Richards struggled with drug and alcohol abuse, mental health problems and homelessness after he got out of prison three months before he killed Barquin. He had served roughly seven months behind bars for violating the terms of his probation on convictions for burglary and other crimes.

Richards, 22, told a judge earlier this month that he was sorry for his crime. He said in a handwritten letter that he wanted to show remorse “for stripping a life from society ... worse, from a loving family.”

Barquin was a top golfer in Spain as a teenager and came to Iowa State to pursue her career.

Her family is aware of Richards’ expression of remorse but “they don’t give too much credit to that apology at this time,” the family’s lawyer, Leon Vidaller, told The Des Moines Register for a story published Thursday.

Authorities have not been able to explain why Richards did it, which makes the loss even worse, Vidaller said. Richards’ family and friends have said his dependence on methamphetamine and other drugs likely led to mental health issues and the violence.

Richards being imprisoned for life — a mandatory sentence — won’t bring Barquin back, but it will give the family some closure, the lawyer said.