Updated at 3:30 p.m. ET
Some of the Marines identified in a video that shows them apparently urinating on the bodies of dead Taliban fighters in Afghanistan were described as "reluctant" to talk to investigators, CBS News national security correspondent David Martin reports.
At least two of the four Marines interviewed by the Naval Criminal Investigative Service, which is conducting the criminal probe, have been uncooperative, Martin reports. The Marines also refused to let NCIS search their belongings.
An NCIS spokeswoman said Friday that the agency has spoken with all four Marines in the video, who are in the United States.
"NCIS investigators are still tracking down information on the individual(s) who created and posted the video as well as initiating computer forensic techniques on the video itself," spokeswoman Maryann Cummings said in a statement.
The Marines could face charges after the military completes its investigation into the incident. The four Marines have been identified as members of a 1,000-man battalion that recently completed a combat tour in Afghanistan and returned to Camp LeJuene, N.C., where they apparently started showing the video around as a war trophy.
The developments come as the Marine Corps appointed a three-star general to decide what, if any, disciplinary action to take against the snipers.
No one has been charged in the case.
Lt. Gen. Thomas Waldhauser will name another officer to lead an internal Marine Corps investigation. He will determine how to proceed once both investigations are completed. Waldhauser is commander of Marine Corps Forces Central Command, whose area of responsibility includes Afghanistan.
Meanwhile, after roundly condemning the Marines' alleged behavior, Defense Secretary Leon Panetta and top military leaders on Thursday sought to contain the damage at home and abroad.
Panetta also said the incident could endanger the prospects for peace talks, although the Obama administration and the Taliban each voiced readiness Thursday to try negotiations while pledging to carry on the military conflict until their rival objectives are met. The separate statements by senior American and Taliban officials illustrated the improved environment for Afghan reconciliation efforts as well as the daunting task ahead.