Published: May 31, 2012 3:51 PM EDT

TAMPA, Fla. (AP) - Police say they've made an arrest in the 2009 slaying of a University of Tampa student.
    
Tampa police announced Wednesday that they've charged 22-year-old David Earl Williams Jr., who was already serving a prison sentence in South Florida for unrelated crimes.
    
Williams is charged with fatally shooting 21-year-old Ryan McCall while robbing the cross-country runner and a friend near the downtown campus in August 2009.
    
Police said Williams was developed as a likely suspect in the weeks after the crime. But it wasn't until recently that other information and tips from the jail allowed investigators to build a case against him.
    
Detectives who went to interview Williams in prison last week said he admitted the robbery, but he said a second suspect killed McCall. However, detectives believe Williams acted alone.

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