A father has gone on trial for allegedly beating and starving his three-year-old daughter to death - three years after her bruised, malnourished body was found at his home.

Donald Lee Cockrell, 30, has pleaded not guilty to murdering Alexis Marie Pounder with his fiancee, Michelle Nicole Smith, in Sandy, Oregon in January 2010.

Smith pleaded guilty to the killing last year and faces a minimum of 30 years behind bars, and as part of the plea deal she will testify against Cockrell.

Alexis, who was known as Lexi, weighed just 21 pounds when paramedics found her beaten body at the garbage-filled home she shared with Cockrell, Smith and four other children under five.

nvestigators said it was one of the worst cases they have ever seen.

The young girl, who had lived at the home since October 2009, was incontinent and was repeatedly punished for soiling herself,