Sam Rainsy is a former finance minister and the main opposition candidate in Cambodia's parliamentary elections.
He was born in Phnom Penh but moved to France to continue his education and career, before returning to Cambodia in 1992.
He was then elected as a member of parliament, representing Siem Reap province, and later appointed finance minister.
However, Sam Rainsy was stripped of the finance minister post after losing a no-confidence vote in 1994.
The following year, he founded the Khmer Nation party (KNP), which changed its name before the 1998 elections to the Sam Rainsy Party (SRP).
Sam Rainsy was elected as an MP for Kompong Chan province in those elections, and the party polled 14 per cent of the vote.
In the 2003 elections, the SRP polled 22 per cent of the vote, losing to Hun Sen, the prime minister and head Cambodian People's Party (CPP).
An 11-month stalemate occurred, where the three main parties competing in the elections could not agree on how to form a new coalition government.
The CPP has been the senior partner in a coalition with the royalist Funcinpec party since 1997.
When a deal was struck, MPs from the SRP boycotted the newly formed national assembly, claiming the other two parties violated constitutional procedures in forming the new government.
In 1997, Sam rainsy nearly fell victim to a grenade attack during a political rally outside the national assembly, which killed at least 16 of his supporters.
He blamed the attack on supporters of Hun Sen, whom he claimed was determined to "seize absolute power by any means".
He went into self-imposed exile in 2005, citing fear of arrest after a vote in the national assembly removed parliamentary immunity from himself, as well as Chea Poch and Cheam Channy, fellow SRP members of parliament.
Sam Rainsy faced multiple criminal defamation charges after accusing the CPP of corruption in the formation of the current coalition government.
He has also accused Hun Sen of involvement in the 2004 murder of Chea Vichea, an SRP-affiliated union leader.
Sam Rainsy was tried in absentia in 2005 in relation to the defamation lawsuits.
The court sentenced him to 18 months in prison and ordered him to pay around $14,000 in fines.
In 2006, he recieved a royal pardon by King Norodom Sihamoni at Hun Sen's request. He then returned to Cambodia in the same year.
Source: Al Jazeera and agencies