A man stabbed a teenager to death before cutting off his head and using it as a puppet and a bowling ball, a court has been told.

James Patrick Roughan, 28, has pleaded not guilty in the Supreme Court in Brisbane to murdering 17-year-old Morgan Jay Shepherd on March 29, 2005.

Instead, he pleaded guilty to a charge of accessary to murder after the fact, but the Crown rejected the plea and is proceeding with a murder trial.