(CNN) -- In a landmark ruling, an international tribunal found former Liberian President Charles Taylor guilty Thursday of aiding and abetting war crimes in neighboring Sierra Leone's notoriously brutal civil war.
It was the first war crimes conviction of a former head of state by an international court since the Nuremberg trials of Nazi leaders after World War II.
Prosecutors, however, failed to prove that Taylor had direct command over the rebels who committed the atrocities, said Justice Richard Lussick of the Special Court for Sierra Leone.
A three-judge panel issued a unanimous decision that Taylor was guilty on all 11 counts of the indictment against him. The judges found him guilty of aiding and abetting rebel forces in a campaign of terror that involved murder, rape, sexual slavery, conscripting children under the age of 15 and mining diamonds to pay for guns.
Prosecutor Brenda Hollis said the verdict "made clear the central role Charles Taylor played in the horrific crimes against the people of Sierra Leone.
"This judgment affirms that with leadership comes not just power and authority, but also responsibility and accountability," she said. "No person, no matter how powerful, is above the law."
Taylor maintained his innocence and pleaded not guilty. A sentencing hearing is set for May 16.
There is no death penalty in international criminal law and Taylor would serve out any sentence in a British prison.
Both prosecutors and defense lawyers said they would examine grounds for an appeal.
Throughout Lussick's read of a long list of chilling crimes, the former warlord remained stoic. Dressed in a charcoal gray suit , a white shirt and a burgundy tie, he stood quietly as the judge delivered the guilty verdict.
The mood was decidedly different in Freetown, the Sierra Leone capital, where, as one resident described it, every television set was on.
"Relief. Relief," said Jennifer Harold, national director of the charity World Vision. "Everybody is thrilled."
Harold said Taylor's conviction was a big psychological victory for his victims. "People can be very cynical about justice," she said. "But now you have someone finally getting caught, finally getting justice."
United Nations human rights chief Navi Pillay described the conviction as "immensely significant," saying it sends out a message that even the most powerful are not above the law.
"It is important to recognize that Taylor may appeal the verdict, and that his guilt is not fully established until the end of the judicial process," Pillay said.
"Nevertheless, whatever the final outcome, this is undoubtedly a historic moment in the development of international justice. A former president, who once wielded immense influence in a neighboring country where tens of thousands of people were killed, mutilated, raped, robbed and repeatedly displaced for years on end, has been arrested, tried in a fair and thorough international procedure."
Prosecutors accused him of financing and giving orders to Revolutionary United Front rebels in Sierra Leone's civil war that ultimately left 50,000 dead or missing. His support for the rebels fueled the bloody war, prosecutors said.
Fighters included teenagers forced to kill, rape and plunder under the influence of drugs to provoke violent behavior.
Witnesses testified about grisly violence by the rebels during the conflict, including chopping off the arms of civilians, and shooting and disemboweling pregnant women and children.
Sometimes, rebels asked people if they wanted long sleeves or short sleeves. The former meant hacking off hands; the latter, forearms.
"Brave men, women and children have taken the stand against Charles Taylor," the prosecutor's office said in a written statement. "They have included amputees, rape victims, former child soldiers, and persons enslaved, robbed, and terrorized. We are awed by their courage."
Prosecutors said Taylor financed the war with proceeds from the so-called "blood diamonds" used to fund rebels in several African conflict areas.
Taylor was president of Liberia for six years until 2003, when heavy international pressure forced him out of office.
He has been on trial since 2007 at the special court for Sierra Leone in The Hague, Netherlands. United Nations officials and the Sierra Leone government jointly set up the tribunal to try those who played the biggest role in the atrocities.
The court was moved from Sierra Leone, where emotions about the civil war still run high.
"While today's conviction brings some measure of justice to the people of Sierra Leone, Taylor and the others sentenced by the Special Court are just the tip of the iceberg," said Brima Abdulai Sheriff, director of Amnesty International in Sierra Leone.
"Thousands of persons suspected of criminal responsibility for incidences of unlawful killings, rape and sexual violence, mutilations and the use of children in Sierra Leone's armed conflict have never been investigated, much less prosecuted."
During the trial, judges heard testimony from more than 100 people, including Taylor and supermodel Naomi Campbell, whom prosecutors put on the stand in an effort to tie him to blood diamonds.
Campbell told the special tribunal that she received "dirty-looking stones" she assumed were gifts from Taylor after a dinner hosted by then-South African President Nelson Mandela in 1997.
"When I was sleeping, I had a knock on my door. I opened the door and two men were there. They gave me a pouch and said, 'A gift for you,'" she said. "The men didn't introduce themselves or say anything else."
Taylor has been a pivotal figure in Liberian politics for decades after he overthrew the regime of Samuel Doe in 1989, plunging the country into a bloody civil war that left 200,000 dead over the next 14 years.
After he was forced out of office, he lived in exile in Nigeria, where border guards arrested him in 2006 as he was attempting to cross into Chad amid international pressure.
Taylor is the first former head of state since the Nuremberg trials to be convicted for war crimes or crimes against humanity by an international tribunal. Adm. Karl Doenitz, who became president of Germany briefly after Adolf Hitler's suicide, was convicted in 1946.
Former Yugoslav President Slobodan Milosevic was tried by an international tribunal but died before a judgment was issued.
The International Criminal Court has charged Laurent Gbagbo, the former Ivory Coast president, with crimes against humanity. It also has a warrant out for Sudanese President Omar al-Bashir, who, so far, has been able to elude arrest.
"Powerful leaders like Charles Taylor have for too long lived comfortably above the law," said Elise Keppler, senior international justice counsel at Human Rights Watch. "Taylor's conviction sends a message to those in power that they can be held to account for grave crimes."