The men were armed and wore black ski masks. In broad daylight, they grabbed Adil Ali el-Aghouri from in front of his house last month, beat him, took him to a rebel military base and threw him in a prison cell.

Ever since, his relatives say, Aghouri has been held without charge or access to a lawyer. His only crime, they say, was to serve in the feared internal security police under Libyan leader Moammar Gaddafi; they insist that he committed no atrocities.

“He’s in prison not because he broke any laws, but by the power of the gun,” said Aghouri’s brother, Muhammad. “This is about revenge.”

With Libya essentially divided in half by conflict, the U.S.- and NATO-backed rebels who control much of the east are carrying out what many view as a campaign of retaliation against those once aligned with Gaddafi, according to relatives and rebel commanders and officials. Such targeting raises questions about the character of the government taking shape in eastern Libya and whether it will follow basic principles of democracy and human rights. Moreover, such acts could further deepen divisions in Libya’s tribal society and diminish the sort of reconciliation vital for stability in a post-Gaddafi era.

Both Egypt and Tunisia, where authoritarian leaders were ousted by popular uprisings, are striving to revise laws and struggling with how to deal with the former members of their regimes. Human rights activists note that Libya’s rebels have had to organize a state, including a new judicial system, in just three months during wartime.

But critics fear the Libyan rebels are going down the same path as Gaddafi — whose government is notorious for carrying out arbitrary arrests, torture and executions without trial — months after launching an uprising based in large part on their outrage over such injustices.

Some critics, including top officials working with the rebel council that runs eastern Libya, also point out that countless Libyans worked in Gaddafi’s government, many just for the paycheck. Those who committed serious crimes have probably fled rebel areas by now, they argue.

“There have been a lot of mistakes, even though the intentions are good,” said Jamal Benour, a judge who is in charge of justice issues for the rebel transitional council. “We need to have a proper judicial process, to build trust in law and order. Now, maybe we’ve lost part of the credibility of the revolution. . . . Some might say that what Gaddafi did in his regime is happening now under the revolution.”

Rebel commanders have created a wanted list and placed suspects under round-the-clock surveillance. Secret militia units raid houses without court warrants and often interrogate suspects for hours. Those released have to sign a document stating their loyalty to the revolution.

As many as 30 civilians are being held at various rebel military bases around Benghazi without due process of law, said human rights activists, judges and prosecutors. In recent weeks, at least seven former members of the internal security police have turned up dead, their bodies riddled with bullets. Although it is not known who killed them, many suspect that they died at the hands of rebel-affiliated death squads.

At a rebel military base in Benghazi, rebel fighters acknowledged that they were rounding up and holding prisoners. They said it was necessary to target and detain civilians because they believed that a “fifth column” of Gaddafi loyalists was trying to retake power within the city, which has become the rebels’ de facto capital.

“On the front lines, you can see Gaddafi’s people. Here, you can’t see the ones in the fifth column,” said Muftah Mahmoud, a rebel fighter in charge of security at the base. “They stab you in the back.”

Mahmoud said detainees are held for three days and then handed over to Benghazi’s prosecutors for trial. But the city’s chief prosecutor, Ali Wanis, said in an interview that he had never received a single case. He described the detentions as “secretive.”

When told of this, Mahmoud shrugged and acknowledged that “the main thing is to keep these people in a secure place until the revolution is over.”

Unlike Gaddafi’s regime, the rebels have given human rights groups, nongovernmental organizations and family members access to the detainees and in most cases appear to be treating them humanely.

But at the same time, in the absence of the Gaddafi-era police and security apparatus, volunteer militias are patrolling the streets, making arrests with no formal legal authority. This, said Tom Malinowski, Washington director for Human Rights Watch, “heightens the risk of vigilante justice and abuse at point of capture.”

“Rule of law has to begin now, or bad habits may become entrenched and later codified as a way of maintaining power,” said Malinowski, who recently interviewed detainees in Benghazi.

So far, the rebel leadership has been unable to rein in the militias under one authority. It also has not set clear rules governing who can be arrested and what their rights are in detention.

“They should be sending these cases to my office for the sake of rule of law,” Wanis said, referring to the detentions.

Seeking ‘a new page’

Abdi Razak Muftah, 33, belonged to a militia that has been rounding up suspected Gaddafi loyalists. Members are trained to watch for anything suspicious.

“There are three guys I know of yesterday who were under surveillance,” Muftah said. “They were going out at night, using their phones in their cars, as if they were getting information. We are following them around, watching what they are doing.”

All three men were former members of the internal security police, although two held low ranks, Muftah said.

Last month, Muftah was ordered to apprehend his neighbor and bring her in for questioning because she held a general’s rank in Gaddafi’s regime. Muftah refused, fearing that if he followed orders, her family would take revenge on his family. So he asked other rebel fighters to bring her in.

They arrived at her spacious house in pickup trucks mounted with heavy machine guns. Some of the masked rebels jumped over the high wall.

The woman’s 18-year-old son, Amar Abdul Baset, said his mother had left Gaddafi’s military in the 1980s and had been a housewife ever since, receiving a pension.

She was interrogated for 12 hours. The rebels peppered her with questions and showed her a list of suspects. They asked whether she was working with anyone on the list or organizing military action for Gaddafi. Before they released her, she was ordered to sign a pledge that she supported the revolution, her son said.

“When she came back, she was very scared,” Baset recalled. “It’s the same tactics Gaddafi’s regime used.”

The family of Aghouri, who was taken from in front of his house last month, initially thought he was dead. His job at the internal security police was to gather intelligence on suspected terrorists. Relatives insist that he was not involved in any killings or torture.

“All he did was follow orders. He committed no crimes,” said Hind Riziq, his wife. “If he did something wrong, he should face a court, not be kept in prison indefinitely.”

His brother, Muhammad, warned that the rebel leadership needed to bridge the divides between Libyans, not widen them.

“There should be a new page, a fresh start,” he said. “Blood will bring more blood.”