The allegations stem from Sarkozy's 2007 presidential campaign.
Bettencourt's former accountant Claire Thibout told police Liliane Bettencourt, the richest woman in France, handed over 150,000 euros in cash and told the money would be given to Sarkozy's treasurer, The Telegraph
According to BBC News
, individual campaign contributions in France may not exceed 4,600 euros.
Thibout also told police in a leaked interview that while Nicolas Sarkozy was mayor of Neuilly (1983-2002), he visited Ms. Bettencourt's house "regularly."
As a result of the allegations, the former president's home was raided
in July, 2012.
Sarkozy's treasurer Eric Woerth resigned
in 2010. Initially, Mr. Woerth refused to resign as he feared it would be taken as a sign of guilt.
As President, Sarkozy was immune to legal investigations, but his judicial immunity
officially expired on June 16.
Mr. Sarkozy has dismissed claims that he accepted all this money as "mere gossip," BBC News
The Bettencourt scandal is not the only criminal probe the former President of France is involved in.
French authorities have confirmed that they are in the preliminary stages of an investigation into the "management" of opinion polls conducted during his time as president, France24
In spite of all the allegations Mr. Sarkozy faces, the former president is rumored to be eyeing a 2017 re-election into office, BBC News
Thursday's Bettencourt hearing is expected to last all day, The Telegraph
Sarkozy's attorney Thierry Herzog said his client could either face preliminary charges or be given "special witness status" and possibly face charges down the line, The Associated Press