A damaged skull may be the oldest murder evidence seen in human history.

The human skull was discovered in Sima de los Huesos, Spain, and dates back 430,000 years, the Public Library of Science reported.

The fascinating site is located within an underground cave system, and holds the skeletons of 28 people who walked the Earth during the Middle Pleistocene. A nearly complete skull found at the site, made up of 52 cranial fragments, reveals two incriminating lesions at the front that are believed to have been inflicted by another human.

The researchers conducted contour and trajectory analyses of the ancient injuries, revealing the traumas were inflicted by two separate blows from the same murder weapon that were most likely purposely imposed by another human being.

The site that the remains were discovered in can only be accessed through a 42-feet-deep vertical shaft, and the researchers are not sure how the bodies ended up there in the first place. The curious accumulation of bodies could be evidence of some of the earliest funerary behavior if the individuals were already dead when they were placed at the bottom of the pit. The team does not believe the injuries are a result of an accidental fall down the shaft because of their location on the skull.

The findings were published in a recent edition of the journal PLOS One.