After a decade behind bars, a former New York City police officer walked out of prison a free man Friday, but his legal troubles are still not over.

Richard DiGuglielmo returned to his family on Sept. 19 after a Westchester judge suddenly overturned his murder conviction. However, Westchester County District Attorney Janet DiFiore says she will appeal the case to higher courts.

?We?ve started the appellate process and we will be appealing that case to a higher court,? DiFiore says.

DiGuglielmo was serving 20 years to life for shooting Charles Campbell to death outside the Dobb?s Ferry Deli in 1996. Police say there was a dispute between Campbell and DiGuglielmo ?s father over a parking spot, which prompted Campbell to retrieve a metal baseball bat. Prosecutors say DiGuglielmo then fatally shot Campbell.

Authorities say DiGuglielmo claimed self-defense but key eyewitnesses saw it differently. A Westchester judge said that two witnesses were coerced into changing their testimony and threw the conviction out.

If DiFiore is successful in her appeal, legal experts say DiGuglielmo would have to return to prison and finish his sentence. If the appeal fails, DiFiore will have to decide whether there is enough evidence to justify another trial.