Abram Wade "Pete" Franklin was awaiting his initial appearance in court on Wednesday after the Mississippi Bureau of Investigation charged the 29-year-old with obstruction in the case, Mississippi Bureau of Investigation spokesman Warren Strain said.
Hattiesburg police Officers Benjamin Deen and Liquori Tate were shot dead during a traffic stop over the weekend.
Of the five suspects charged, just one is accused of pulling the trigger.
Marvin Banks, 29, appeared in court on Monday and was charged with two counts of capital murder, along with counts of grand theft auto and being a felon in possession of a firearm, Strain said.
The shooting unfolded Saturday night after Deen, 34, stopped a vehicle for a speeding violation
, then called for backup after he found probable cause to search the car, Strain said. Shots were fired at some point after Tate, 24, arrived at the scene to help, he said.
Preliminary autopsy findings revealed that one officer was shot in the back, and the other was shot in the face, Strain said.
Investigators haven't said what motive they believe Banks had for allegedly opening fire or specified what role the other suspects played in the shooting. Tests have begun on boxes of evidence, but it could be weeks before the results come in, Strain said.
"There are theories, but we'll wait on the forensics to come back," Strain told reporters this week.
Marvin Banks' half-brother, 26-year-old Curtis Banks, was charged with accessory after the fact of capital murder, Strain said.
Joanie Calloway, 22, was originally charged with two counts of capital murder, but her charges were reduced in court on Monday to accessory after the fact of capital murder, Strain said.
Cornelius Clark is charged with obstruction of justice.
None of the suspects entered pleas in court Monday. As deputies escorted him into a police station Sunday, Curtis Banks wailed and repeated "I didn't do it."
A community mourns
The shooting marked the first time in 30 years that an officer was killed in the line of duty in Hattiesburg, Mayor Johnny DuPree told CNN.
"The men and women who go out every day to make sure that we are safe were turned on," DuPree said.
Mississippi Gov. Phil Bryant said he and his wife, Deborah, were mourning the officers' deaths.
"This should remind us to thank all law enforcement for their unwavering service to protect and serve," he said in a statement. "May God keep them all in the hollow of his hand."