The Santa Clara County district attorney's office has declined to file charges against San Francisco 49ers defensive lineman Ray McDonald in a felony domestic violence investigation stemming from his Aug. 31 arrest.

Prosecutors said in a release that they were unable to charge McDonald because of conflicting versions of what happened, a lack of verifiable eyewitnesses and a significant lack of cooperation by the alleged victim, McDonald's fiancee.

The arrest came only days after NFL Commissioner Roger Goodell announced stiffer penalties for players accused of domestic violence, including a six-week suspension for a first offense and at least a year for a second.