KENTON — Three people facing high-level felonies over the overdose death of a Lima teenager last year have asked a judge to push back their trial dates.The trial for Austin T. Griesheimer, 21, of Ada, was pushed back to Aug. 20 and is expected to take three days. Amanda L. Johnson, 20, of Lima, and Derek T. Mullett, 19, of Ada, have asked the Hardin County Common Pleas judge to rescheduled their trials, as well.All three have pleaded not guilty to involuntary manslaughter, corrupting another with drugs, permitting drug abuse and aggravated possession of drugs. Mullett also is charged with tampering with evidence and has pleaded not guilty to that charge.Johnson was scheduled to stand trial June 6 while Griesheimer and Mullett, both had trials set for this month. Johnson also has hired a new attorney.The charges stem from the May 1, 2011, death of 19-year-old Emily Christen at an Ada home. Christen died of an overdose of oxymorphone, a painkiller, officials said.The three are accused of purchasing oxymorphone in Lima and sharing the drug with Christen at Mullett’s home on state Route 309 near Ada. Griesheimer is accused of driving his car to Lima to get the drug while Mullett is accused of taking steps to alter or destroy evidence. Christen’s body was discovered inside the house on May 1. Authorities have said the crimes took place between April 30 and May 1, 2011. Christen was a 2010 graduate of Lima Central Catholic High School. If convicted of all charges, Mullett faces up to 25 years in prison and Griesheimer and Johnson, each face up to 20 years.You can comment on this story at www.limaohio.com.