James McCray, who is currently in jail in Charles County in Maryland, testified Wednesday. McCray, who said his real name is Jason Lee, told the jury he got to know Michael Maurice Johnson after he moved to Baltimore from New York six years ago.
McCray has testified for the prosecution in another murder case, The Baltimore Sun reported. Johnson's lawyers called him a "jailhouse snitch."
Johnson is charged with killing Phylicia Barnes, 16, whose body was found in the Susquehanna River. Prosecutors have little direct evidence against him.
McCray said Johnson called him and said he had a "serious matter." He said when he went to Johnson's apartment Phylicia's body was in the bedroom and Johnson said he had "forced himself on her."
"After that, she wouldn't stop crying. He couldn't get her to stop crying, so he killed her. He said he choked her," McCray said.
McCray said he did not help Johnson get rid of the body but did give him some advice, including putting it in water instead of burying it to destroy evidence of sexual intercourse.
He said he only told police about what he had seen in 2012 after reading the Bible in jail.