A Cobb County couple waits for answers in the death of their son, shot and killed by police 10 months ago.

Authorities tell Rob and Carolyn Murdock an internal investigation into their son Matthew's death remains open in what they describe as "revisionary" mode.

The couple has hired an attorney to help, but the attorney cannot do anything until the police investigation of Officer Sean Henry is complete and police reports, call logs, car video and autopsy results are released.

"He shot my son in the back," said Matthew Murdock's father Rob.

What happened to the 34 year old man that night in May 2011 remains a mystery a for now, Henry remains on desk duty.

A grand jury looked into Murdock's death and concluded Henry was authorized to discharge his weapon.  They did not recommend any criminal charges be filed.

"He had been working," his mother said.  "He was just going home late at night.  He was in a bad part of town, but that's where his job was. They approached him and we still don't know why."