Following the assassination last week of their military commander, Abdel-Fatah Younes, Libya's shaken rebels are rooting out Qaddafi elements in their ranks, Reuters reports. 

The rebel leadership insists the slaying was the work of Qaddafi's regime, but several witnesses say Younes was killed by fellow rebels after he was summoned for questioning about continued ties to his former masters in Tripoli.
As officials pieced together events leading up to Sunday’s gun battle between rebel factions, they announced that a faction of fighters called al-Nidaa was actually made up of Qaddafi loyalists posing as rebels. 
The revelation could raise questions about the loyalty of individual rebel factions and sap the movement of much-needed unity in its push to topple Qaddafi some six months after the revolt began.
Suspicions about al-Nidaa were confirmed, a rebel security leader said, when intelligence officials determined the group was behind two prison break’s on Friday in the rebels’ de facto capital of Benghazi that freed 200 to 300 inmates, including pro-Qaddafi mercenaries, fighters and other regime loyalists.
“These people took advantage of the chaos that resulted from the killing of Younis and entered and attacked the military prison and the (civilian) Kuwaitiya prison,” rebel deputy interior minister Mustafa al-Sagezli said
On Sunday before dawn, rebel forces tracked al-Nidaa members to a factory where they were hiding out and sent in negotiators to try to persuade them to surrender. When they refused, the rebel units besieged the factory, killing four of the Qaddafi fighters, said rebel Information Minister Mahmoud Shammam.
A battlefield commander who participated in the operation, Ismail Salabi, said four of those posing as rebels were also killed and 25 were captured. He described them as Libyans from the southern part of the country who belonged to the Qaddafi Brigades.
“This is a hard hit for the fifth column,” he said.
Rebel forces also seized 40 of the escaped prisoners, who were found hiding out with the fighters.