1MDB president and executive director Arul Kanda may have given a summary on where the company spent its RM41.8 billion but former premier Dr Mahathir Mohamad is unconvinced.
This, he said, is because Arul Kanda has on various occasions been caught lying and therefore cannot inspire confidence.
"I am intrigued by the ability of 1MDB to invest RM42 billion in so many businesses.
Really I should be fully satisfied with how 1MDB expended the huge loan that it borrowed. But unfortunately I am not.
I am not, because the information came from the current executive director, Arul Kanda and Arul has been caught lying quite a number of times," he said in a blog posting today.
In particular, Mahathir took issue with Arul's explanation over 1MDB's US$1.103 billion (RM4.1 billion) investment in the Cayman Islands which the later claimed have been fully redeemed and later parked in Singapore.
"He (Arul) must have told the prime minister about this fantastic pile of dollar notes so the prime minister answered the question in Parliament that the cash is in a bank in Singapore.
"It cannot be brought back because Bank Negara asks too many questions. The finance minister must approve or disapprove all Bank Negara strictures or approvals.
Then the Singapore bank denied that the cash was in its bank (in Singapore). Embarrassing. The vision has disappeared.
"No. It is not cash. It is documents. No, it is units. What units? Dunno (sic) . Which bank? Not clear. The mystery deepens," Mahathir in sarcastic full form.
Missing details on controversial deals
Mahathir was referring to the embarrassing episode where Najib was forced to change his answer in Parliament about where and what exactly 1MDB's funds were in Singapore.
"Arul (photo ) had lied before. It is not inconceivable that on the RM42 billion, Arul may be lying again.
"Where a chunk of the RM42 billion went is still questionable," added Mahathir.
He also questioned the details of Arul's explanation about where the RM41.8 billion was spent including if to pay taxes.
"Do people use borrowed money to pay tax? What tax? No profit was declared but tax was paid. How much? Cost of managing 1MDB runs into billions!
"In any case, many names which are known to have received money from 1MDB are not mentioned.
"Lots of money went to Hong Kong companies with funny names," he said.
Mahathir then demanded for more details of controversial dealings with PetroSaudi, billionaire Jho Low and Brazen Sky.
"Jho Low denies but why has he not proven that he did not receive US$260 million (RM988 million) from 1MDB to buy a bank," he said.
Finance Minister II Ahmad Husni Hanadzlah took to live television to explain about 1MDB last week but was coy about Jho Low, insisting he did not want to ' glamourise ' the billionaire.