An off-duty security guard who stabbed a woman he had met at a Southeast Portland bar 20 times and left her in a pool of blood on the sidewalk was sentenced Friday to 15 years in prison.

Investigators said they don’t know why Timothy Lee Beasley, 36, unleashed such violence against the woman -- more than was necessary to rob her of her purse at about 3 a.m. on June 26, 2017.

Beasley was a security guard at the Belmont Inn, a bar near Southeast 34th Avenue and Belmont Street. He wasn't working earlier that night when Beasley and the woman hit it off and started kissing, investigators said.

After the bar closed, the pair began to walk toward Sunnyside Park when Beasley started hitting the woman's head against the sidewalk and then stabbed and cut her with his knife, investigators said.

A neighbor, who heard what he thought might be an “animal fight” came out of his home and yelled at Beasley, who ran off while taking the woman's purse with him.

Beasley pleaded no contest to attempted murder and first-degree robbery in Multnomah County Circuit Court.

"This case involves extreme violence and the victim in the case is going to have to live with her injuries for the rest of her life, both the physical injuries and emotional injuries caused by Mr. Beasley,” Deputy District Attorney Todd Jackson said in a statement after sentencing.

Jackson said the woman supported the plea agreement, which called for the 15-year prison sentence. Beasley also was ordered to pay $8,512 in restitution.

-- Aimee Green