SIOUX FALLS, S.D. (AP) — A Sioux Falls man convicted of first-degree manslaughter in the stabbing death of his girlfriend has been sentenced to 20 years in prison.

Authorities say Michael Martinez stabbed 21-year-old Beverly Guerra 14 times with a knife during an alcohol-fueled argument in their apartment in July 2014. He was convicted last fall of manslaughter but acquitted of murder.

Judge Susan Saber sentenced Martinez on Monday, saying the incident did not warrant a light sentence but also did not call for the maximum punishment of life in prison. She called the 20-year sentence "middle ground."

Members of Guerra's family say they don't think justice was served.

Guerra's 3- and 6-year-old children were in a back room when she was killed. They were put in the custody of social service officials.

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