WASHINGTON, July 27 (UPI) -- The Pentagon is trying to find out who leaked thousands of secret military papers to an Internet whistle-blower, a U.S. military spokesman said Tuesday.

Marine Corps. Col. Dave Lapan said the Army's Criminal Investigation Division is spearheading the investigation in WikiLeaks' posting of 90,000 documents related to the Afghanistan and Iraq wars, the Defense Department said in an article.

"An investigation has been initiated, (and) Army CID has the lead," Lapan said, adding the division was chosen for its expertise in such matters.

He said the division also is investigating the case of Army Spc. Bradley Manning, charged with leaking a video of a U.S. helicopter attack in Iraq to WikiLeaks. While the new leaks probe is a continuation or extension of the investigation of Manning, the documents case is "broader," Lapan said.

"The current investigation into the leak of the documents to WikiLeaks isn't focused on any one, specific individual," Lapan said. "It's much broader. They're going to look everywhere to determine what the source may be."

In an MSNBC interview, Pentagon Press Secretary Geoff Morrell said Manning "is a person of interest with regards to this leak, but we just don't know at this point."

Morrell said the issue of whether the documents leak damaged operational security or endangered U.S. forces hadn't been determined, saying "we're still trying to get our arms around that."

"And are there any things in there that could jeopardize our operations or our nation's security?" he said. "We just don't know at this point."