OLATHE, Kan. – A man convicted of killing his social worker by stabbing her and cutting her with a chain saw was sentenced Thursday to life in prison with no possibility of parole for 50 years.

Andrew Ellmaker, 20, of Overland Park, was convicted in May of first-degree murder in the August 2004 stabbing death of Teri Lea Zenner, 26.

He also was convicted of aggravated battery for injuries his mother, Sue Ellmaker, suffered while trying to protect Zenner.

Judge Peter Ruddick could have sentenced Ellmaker to life in prison with no possibility for parole for 25 years. He picked the harsher sentence after hearing an impassioned plea from Zenner’s family for at least 50 years behind bars _ the harshest punishment available in Ellmaker’s case.

Prosecutors could not seek a harsher sentence because Ellmaker was 17 when he killed Zenner. In Kansas, juveniles are not eligible for the death penalty or life in prison with no chance of parole.

“This world will never get to reap the benefits that Teri brought,” Zenner’s husband, Matt, said tearfully. “She’s gone forever and so should the man who murdered her.”

Zenner, who worked for the Johnson County Mental Health Center, was visiting Ellmaker’s house to make sure he was taking his medication.

According to testimony at Ellmaker’s trial, he trapped Zenner in his bedroom. When his mother heard Zenner crying and threatened to call police, Zenner came stumbling out of the bedroom with a stab wound to the neck.

Ellmaker’s mother was stabbed repeatedly after throwing herself between her son and Zenner. After his mother escaped to a neighbor’s house, Ellmaker retrieved a chain saw from his bedroom and used it on Zenner.

Prosecutors said a harsh sentence was warranted because the crime was heinous. Defense attorneys said Ellmaker was mentally ill, though did not use that as a defense during the trial.

A service of the Associated Press(AP)