DEKALB COUNTY – (WAOK/AJC)  -  Police say a bank robbery suspect is in custody after he tried to hold up a Citizens Trust Bank this morning in DeKalb county.   Witnesses say the would be robber walked into the bank,  off of S. Hairston Road,  waving a gun,   and was confronted by a security guard who shot him in the knee.  Another bank employee was slightly injured in the gunfire.   The security guard was not hurt.   The unidentified suspect was taken to a hospital for treatment.