The military is investigating the deaths last week of a U.S. Marine and a Navy Corpsman believed to have been killed in a friendly fire incident in Afghanistan, military officials tell FOX News.

Within 72 hours of the deaths, a team of investigators were launched from Creech Air Force base in Nevada to confirm suspicions the two men were killed by a Predator drone strike, according to a defense official familiar with the investigation.

All U.S. military Predator drones are piloted out of Creech.

A second investigating team operating out of Afghanistan is poring over black box cockpit recordings and all the data that was recorded during the incident. It will take about a week to gather the data and then another week to conduct on the ground interviews with those involved in the incident, sources tell FOX News.

One official stressed that at this point the incident is being treated as a suspected fratricide. Officially, ISAF and the Pentagon won't comment beyond saying the incident is under investigation.

Staff Sgt. Jeremy D. Smith, 26, of Arlington, Texas and Seaman Benjamin D. Rast, 23, of Niles, Mich., were conducting combat operations on April 6th in Helmand province when they were killed.

Smith was assigned to the 1st Battalion, 23rd Marine Regiment, 4th Marine Division, Marine Forces Reserve, based out of Houston, Texas. Rast was assigned as a hospitalman to the 1st Battalion, 23rd Marine Regiment, 2nd Marine Division and was stationed at Naval Medical Center, Expeditionary Medical Force Detachment, San Diego, Calif.

Rast's father was the first to tip news media to the idea his son might have been killed by a U.S. drone.

President Obama has significantly increased drone stakes, particularly clandestine operations, since taking command two years ago.