Defense attorneys filed a motion last month to have the file sealed in an effort to control pretrial publicity.
The order to seal the case, written by Lee County Circuit Court Judge Jacob A. Walker, says the county district attorney's office supported the motion.
The order means the public cannot access Lockhart's file through the circuit clerk's office.
A gag order had already been issued to keep anyone involved in the case from publicly discussing it.
Lockhart is 23 and is from Smiths Station. He is charged in the March 4 murder of Auburn freshman Lauren Burk, of Marietta, Ga. Lockhart is also charged with a February robbery in Russell County.
No trial date has been set.