Long seen as Arafat's likely successor, Barghouti was the West Bank chief of Arafat's Fatah faction and a once prominent supporter of the Oslo peace process. In a twist that puzzled some Israelis, he became a key leader of the violent uprising that followed the collapse of peace talks in late 1999.
The 44-year-old Barghouti was convicted today by an Israeli civilian criminal court in Tel Aviv for his role in the killing of five Israelis in attacks by Fatah militants. Israel accused him of managing and financing militants to carry out the attacks.
Barghouti denied wrongdoing. He argued that the court had no right to try him because he is an elected official and was abducted illegally in the occupied West Bank.
A senior Arafat adviser, Nabil Abu Rdeineh, reacted to the verdict today in Ramallah by saying, "This is an illegal action from the Israeli government. They don't have the right to sentence Mr. Barghouti. This is an illegal action, and we consider this Israeli action as another crime against the Palestinian people. He is a member of parliament, an elected member of parliament, and the Israelis are doing the wrong thing."
Rdeineh also dismissed a statement by the judges, who said Barghouti's orders for attacks on Israelis were sometimes "based on instructions" from Arafat.
In their verdict, the judges wrote: "Arafat would never give explicit instructions for attacks, but he let it be known when the timing was right." They added that Arafat made sure his subordinates knew when he wanted a cease-fire and when he wanted attacks.
Seized by Israel in 2002, Barghouti denied orchestrating attacks. He has expressed pride in Palestinian resistance to Israel while declaring his opposition to the "killing of innocents."
Analysts say today's verdict is likely to bolster Barghouti's standing among Palestinians. Akiva Eldar, chief political columnist for "Ha'aretz," a liberal Israeli newspaper, said: "Barghouti was one of the leading young Palestinian leaders who was willing to discuss peace with the Israelis. He has many Israeli friends. He speaks Hebrew fluently. And I think he represents and his sentence represents, in a nutshell, the whole crisis between us and the Palestinians."
Eldar tells RFE/RL that he believes the case fits Israeli Prime Minister Ariel Sharon's policy of seeking to discredit the Palestinian cause by marginalizing prominent leaders who enjoy genuine popular support: "I think that locking him up for the rest of his life helps that school in Israel that argues that we don't have [credible Palestinian] partners because they are locked up. Arafat is locked up in a way in Ramallah. Barghouti is locked up in jail. And it seems that every possible Palestinian partner [is locked up]. And I mean partner as someone who can offer the Palestinian people a deal which they can buy, not a deal that Israel wants them to buy."
Barghouti's conviction comes at a time of high tension, coinciding with Israel's bloodiest raid in Gaza in years, which has sparked international outcry over the killing of some 30 Palestinians.
The court found Barghouti guilty of murder in attacks that killed a Greek Orthodox monk -- an Israeli national -- in the West Bank in 2001, an Israeli at a Jewish settlement in 2002, and three people at a Tel Aviv restaurant in 2002. He was also convicted on one count of attempted murder.
The court, which asked for five life sentences, found insufficient evidence to deliver guilty verdicts in the killings of more than 20 other Israelis listed in the indictment. Sentencing is set for 6 June.
Once in favor of pragmatic relations with Israel, Barghouti became known for his fiery rhetoric after the intifadah erupted in 2000 and he became associated with the militant group Al-Aqsa Martyrs Brigade.
The metamorphosis prompted some on the Israeli left to ask what had happened to the man they once regarded as a peace partner.
Barghouti said Israel society had changed radically after the 1995 assassination of Israeli Prime Minister Yitzhak Rabin, a key peace supporter.
Shortly before his arrest, an Israeli interviewer suggested that Rabin would not have supported peace had he known that Palestinians like Barghouti would later turn violent. Barghouti replied: "Between 1967 and 1993, [Israel] built 25,000 apartments in the territories. Between 1993, after Oslo, and 2000, [Israel] built another 23,000 apartments in the territories. Had we known that this is what was going to happen, we also wouldn't have started this process."
Barghouti received an open civilian trial rather than a closed military one. Analysts say that by holding public sessions, Israel sought legitimacy for crackdowns on Palestinians that have divided Israeli public opinion.
Palestinian official Qaddora Fares said today that the sentencing will raise Barghouti's popularity among Palestinians to something like that of the jailed Nelson Mandela, the apartheid-era South African dissident who later was released and became president on a wave of popular support.
But for Israeli columnist Eldar, Barghouti's conviction is simply the result of a series of fatal mistakes both sides have made since the peace process began more than a decade ago.
"Barghouti is perceived as a man of peace in the occupied territories, and I think that if both sides didn't make so many mistakes on the way since Oslo, Barghouti could be now one of the prominent leaders of a Palestinian state, a Palestinian government. This is another unfortunate result of the mistakes and misunderstandings along this way."