WASHINGTON – Despite gaining their freedom by signing pledges to renounce violence, at least seven former prisoners held by American officials at Guantanamo Bay, Cuba, have returned to terrorism, at times with deadly consequences.

At least two are believed to have died in fighting in Afghanistan, and a third was recaptured during a raid of a suspected training camp in Afghanistan, a Pentagon spokesman, Lieutenant Commander Flex Plexico, said. Others are at large.

Additional former detainees have expressed a desire to rejoin the fight, be it against U.N. peacekeepers in Afghanistan, Americans in Iraq, or Russian soldiers in Chechnya.

Some 146 detainees have been released from Guantanamo, but only after American officials had determined the prisoners no longer posed threats and had no remaining intelligence value.

Pentagon officials acknowledged that the release process is imperfect, but they said most of the Guantanamo detainees released have steered clear of Islamic insurgent groups.

The small number returning to the fight demonstrates the delicate balance America must strike between minimizing the appearance of holding people unjustly and keeping those who are legitimate long-term threats, Bryan Whitman, a Pentagon spokesman, said.

Human rights groups frequently criticize the Defense Department for holding hundreds of prisoners at the naval base, largely without charges or legal counsel. Many have been held for more than two years; only a few have been charged.

An additional 57 Guantanamo prisoners have been transferred to the custody of their home governments: 29 to Pakistan; seven to Russia; five each to Morocco and Britain; four each to France and Saudi Arabia, and one each to Spain, Sweden, and Denmark, the Pentagon has said.

The Pentagon did not identify the seven detainees believed to have returned to fighting, although a few names have been made public. One released detainee killed a judge leaving a mosque in Afghanistan, Lieutenant Plexico said.

Those in the small group that has gone back to fighting come mainly from the upper echelons of suspected terrorist groups, some allegedly linked to Al Qaeda, several counterterrorism officials in the Middle East said. They gave no details, but one noted a trend that lower-echelon members tend to get on with their lives after they are released.

The former prisoners include Abdullah Mehsud, a former Guantanamo Bay detainee linked to Al Qaeda who oversaw the recent kidnapping of two Chinese engineers in Pakistan.

Last Friday, Pakistani soldiers began a massive search for Mr. Mehsud, 28, who returned to Pakistan in March after about two years’ detention at Guantanamo. Pakistan officials say he has forged ties with Al Qaeda since then.

One of the two former prisoners killed is Maulvi Abdul Ghaffar, a senior Taliban commander in northern Afghanistan who was arrested about two months after an American-led coalition drove the militia from power in late 2001.

He was held at Guantanamo for eight months, then released, and was killed about a month ago, on September 26,by Afghan security forces during a raid in Uruzgan province. Afghan leaders said they believed he was leading Taliban forces in the southern province.

Major General Eric Olson, the no. 2 commander of American troops in Afghanistan, said this month there was no alternative to releasing prisoners from Guantanamo.