The former head of Abu Dhabi's sovereign wealth fund was arrested in Abu Dhabi as part of a graft investigation into Malaysian state fund 1MDB, according to a report. Meanwhile, an elusive Malaysian at the heart of the probe may have been spotted off Hong Kong.

Khadem Al Qubaisi has emerged as a key figure in a global investigation into alleged fraud at 1MDB, «The Wall Street Journal» reported, citing several people familiar with the matter.

Qubaisi, who formerly presided over Switzerland's Falcon Private Bank as chairman, isn't the first arrest in the 1MDB case, but he is by far the most prominent and formerly influential.

High-Profile Execs, Officials

His arrest represents a widening of a global investigation into 1MDB and allegations that billions in state funds were siphoned off for private use, ultimately financing luxury New York and Beverly Hills real estate, fine art, and even Hollywood film «The Wolf of Wall Street».

A lawyer for Qubaisi, who does not face any charges presently, declined to comment to the newspaper. He has previously not been allowed to leave the United Arab Emirates and had his assets there frozen. Qubaisi is also the subject of a Swiss probe.

Jho Low Spotted?

The move comes as a U.S.-led probe into 1MDB heats up and threatens other high-profile executives and officials, including Malaysian Prime Minister Najib Razak.

The PM isn't named in U.S. filings, but can be identified through a description of his role.

One of the most elusive figures in the 1MDB scandal, Jho Low, has yet to be seen in public since the scandal. The «South China Morning Post» reported that a luxury yacht which reportedly belongs to Low was spotted entering Hong Kong waters.

The investigation into 1MDB in at least seven countries has ensnared countless banks, including UBS and Falcon Private Bank.