MILWAUKEE (AP) _ A 14-year-old girl was sentenced to 34 years in prison for joining two teen-age brothers in the murder of a disabled woman who was stabbed in her apartment and robbed of $3.

``I'm at a loss to understand why you took part in this,'' Judge Jeffrey Kremers told Jessica Lynn Coulson, who wept as she was sentenced Friday.

Cheryl Straetz, 48, who had multiple sclerosis, was killed Dec. 16. She had been stabbed and cut 29 times, an autopsy found.

Jacob Baker, 15, identified as the stabber, and Coulson were tried as adults. Baker also was convicted of murder and received a 50-year prison sentence.

The third assailant, Baker's 16-year-old brother, was sentenced to detention until age 25.

The Straetz family sent letters to the judge saying Coulson ransacked the apartment during the assault.

``Jessica wanted a sock stuffed into my sister's mouth because she was making too much noise,'' Nicholas Straetz wrote.

The three teens broke into the apartment as part of a ``big adventure'' to get money, according to court documents.