Police in Israel detained the businessman Beny Steinmetz and four others for questioning in a money-laundering investigation involving real estate deals abroad.

The five were questioned Monday under caution, meaning they are considered suspects in the case, The Times of Israel reported. They are accused of money laundering, falsifying documents, using fake documents, false registration of corporate documents, fraud, breach of corporate trust, obstruction of justice and bribery, police said.

Raids were also carried out at their homes and offices, according to The Times of Israel. The other four suspects were not named, but a media report identified one as a well-known figure in Israeli banking.

A police source told The Times of Israel that Steinmetz was the prime suspect in the case.

Steinmetz, who made billions as a diamond and mining magnate, was arrested in December and accused of paying millions of dollars in bribes in the Republic of Guinea in exchange for advancing his business interests there. He was held under house arrest at the time and later released.

Steimetz has consistently denied any wrongdoing, calling the allegations against him the result of a conspiracy designed to make his firm relinquish its legally owned mining rights.

An Israeli media report said the current probe is linked to the Africa investigation.

According to Forbes, Steimetz is worth £786million ($1.02 billion), making him one of Israel’s richest people.