Body parts from all 150 victims of the Germanwings plane that crashed in a remote and mountainous section of the French Alps last week have been found, French prosecutor Brice Robin said Thursday. Workers have found 2,854 body parts in more than a week of searching and combing through wreckage, the Associated Press reported.

Not all of these parts have been traced back to the people that had been on board the plane, which was en route from Barcelona, Spain, to Düsseldorf, Germany, when it crashed. A French official has warned that it could take up to four months to match all the body parts with victims, using DNA provided by families.

Recovering the body parts, scattered amid debris and other wreckage from the crash, was an arduous process that required helicopters and specialized gear for the investigators and forensic teams involved. Local climbers pitched in as well, sharing their expertise and familiarity with the terrain. Most pieces of the Airbus A320 were no larger than a car door, the AP reported. French investigator Col. Patrick Touron has said that while bodies would be returned to their families as soon as possible, the process would be long.

In the week since the crash, investigators have struggled to piece together why co-pilot Andreas Lubitz appeared to lock his captain out of the cockpit so he could deliberately crash the plane, combing his records as a pilot and his medical history for evidence of depression and other issues. Evidence surfaced Thursday that he researched possible suicide methods and cockpit security.

News also broke Thursday that workers had found the second so-called black box, buried in a ravine that had previously been explored multiple times. Robin, the French prosecutor, said the box was “completely blackened” but that it was still “possibly usable,” the AP reported.