A French judge has placed an uncle of Syrian President Bashar al-Assad under formal investigation on suspicion of tax fraud and money-laundering, a source close to the case said on Tuesday.

Suspected of having acquired his wealth in France illegally, Rifaat al-Assad, a political opponent of his nephew, was placed under investigation on June 9 after an interrogation with a French financial judge, the source said.

Rifaat al-Assad has lived in exile since the 1980s after he sought to oust his older brother, the late Syrian president Hafez al-Assad, who was Bashar’s father. The judge banned him from leaving France apart from trips to London for health reasons.

Anti-corruption associations filed complaints against Rifaat in 2013. The following year, French authorities began looking into whether there was evidence of corruption, bribery and money-laundering.

Rifaat’s lawyer declined to comment. At the time the complaint was filed, people close to him said his wealth, which includes numerous apartments and buildings in Paris, did not come from Syria.