This was also my first thought, however they claim that was just sewage:
"The stinking reddish liquid turned out to be sewage that penetrated the sarcophagus through a small crack and completely flooded it from the inside. At the nearest inspection it was found out that in this ignoble vein the heavily decomposed remains of not one, but three people floated."
"The stinking reddish liquid turned out to be sewage that penetrated the sarcophagus through a small crack and completely flooded it from the inside. At the nearest inspection it was found out that in this ignoble vein the heavily decomposed remains of not one, but three people floated."