The commission also requested an interview with Mr. Assad over the summer as the investigation got under way, but was rebuffed.
In this case, however, the commission requested reformulation in the absence of adequate data.
Mr. Cotler said the commission requested that material this morning.
The commission has also requested access to Bagram and other bases, he said.
The new request will extend a delay that the commission requested in January.
Once created, the second commission could request money from the city, according to the group's counsel, Jerry H. Goldfeder.
He was afraid throughout most of his presidency that the commission would request that he be prosecuted for crimes against peace.
Separately, the commission has requested information about trading in shares of companies before and after such financings are completed, according to people briefed on the matter.
In March of this year, the commission formally requested proposals from contractors.
But the commission requested more money earlier this year saying that reports of alleged violations of the Federal election law had reached "unparalleled scale."