BENGHAZI, Libya (Reuters) - The face of a young man looks out from billboards across Benghazi. "A mother's cry. If my son is guilty, bring him to justice. If he is innocent, let him go," says the caption, which ends with a phone number.
Speaking at the family home, the mother, Ansaf Ibrahim, recounts how dozens of militia fighters from the February 17 Brigade stormed in on August 30 and seized her husband Ali Muftag al-Warfalli and their son Firas, 21, a dentistry student.
The brigade, named for the start date of the revolution that toppled Muammar Gaddafi, is one of the largest and most heavily armed militias prowling Libya a year after the civil war ended. Most operate with the permission of the weak central government. They answer to their own leaders and maintain their own jails.
Such arrests, described by many Libyans as kidnappings, are fuelling a backlash, which has intensified in the days since the killing of U.S. ambassador Christopher Stevens and three other Americans in an attack on the U.S. consulate.
Ansaf Ibrahim says a few people have called in response to the billboards but so far they have not been able to help, offering only sympathy. "One person called to say his own mother fell sick with grief when she saw the billboards."
The militia say their powers to arrest and detain people are vital to protect a country where the police and security forces are too weak to maintain order.
February 17 says it has turned the two al-Warfalli prisoners over to the military police. A member of the brigade's High Security Committee said Ali Muftag, the father, was held on suspicion of having ties to Gaddafi loyalists in Egypt and Firas on suspicion of links to militants who set off bombs in Tripoli.
Ansaf Ibrahim says both men are innocent.
She believes her son was taken in just because he was at home when the militia arrived to arrest her husband, who was a student in Britain in the 1980s when pro-Gaddafi students inside the Libyan embassy were blamed for shooting a policewoman.
"Whatever they think the father has done, that doesn't mean my son has done something too. If you want the father, you do not have to take the son in this horrible, frightening and savage way," she said.
Activists who speak out against the detentions say they frequently become targets too.
Journalist Sherifa al-Senoussi al-Fsay, who has criticised militia abductions in television broadcasts, was pulled off the street in May after leaving the home of a detainee's family. A car pulled up and armed men jumped out.
"They took my bag and searched it. They saw my journalist ID. I was yelling, saying I was a journalist," she recalled.
"I was trying to make them stop. One of them grabbed my veil. They tried to haul me away. I wriggled free and ran to a building. I tried to ask for help but one of the men grabbed me and dragged me across the ground. They took me to the car, threw me inside and beat me."
She says she was driven to a deserted spot and bundled into another car with another group of armed men, who also hit her.
Finally, she was delivered to a police station in central Benghazi. Activists demonstrated outside to demand her release and, after two days, a sympathetic militia leader sent armed men into the police station to free her.
Four months later, al-Fsay still does not dare say which of the hundreds of armed groups she blames for having captured her, fearful they will retaliate.
The government says it is taking steps to rein in the militia. Those that operate without government permission are being dissolved, while those that have government permission are being incorporated into the regular army's chain of command.
The government said on Monday it was replacing the civilian leaders of February 17 and another powerful Benghazi militia that also operates its own jail, Rafalla al-Sahati. The leaders of the two militias, among the most powerful men in the country, are to be replaced with uniformed army colonels, putting their forces fully under the army chain of command.
The billboard pictures of Firas al-Warfalli stared down as thousands of Libyans demonstrated over the weekend against militias on a march known as "Rescue Benghazi Day".
The protesters seized bases of the Islamist militia Ansar al-Sharia, which did not have government permission and which Washington suspects of having had some kind of connection to the attack that killed Ambassador Christopher Stevens.
The demonstrators then marched on the heavily fortified compound of Rafallah al-Sahati, one of the biggest militias that operate with government approval. The protesters looted the compound and freed prisoners. The authorities backed the militia the following morning and its base is again occupied.
At the al-Warfalli house, Firas's 10-year-old brother comes into the room where his mother is meeting journalists, poses for a snapshot and scampers out. "My little son has a new game he plays," his mother says, imitating a small boy pretending to fire a machine gun. "He says: ‘I'm going to kill February 17 and get my father back for us.'"
editing by Janet McBride