More than 100 human skulls and remains belonging to infants have been discovered inside the home of a man accused of desecrating mausoleums and gravesites.

Jonathan Gerlach, 34, faces more than 500 charges relating to the alleged offending, which allegedly began around Halloween in what authorities have described as a 'horror movie come to life.'

The Pennsylvania local allegedly had collected skulls, long bones, mummified feet and decomposing torsos, storing them in his basement and a separate storage locker, Delaware County District Attorney Tanner Rouse said.

'Very simply, detectives have recovered an awful lot of bones at this point, and we are still trying to piece together who they are, where they are from, and how many we are looking at,' Rouse said.

'Detectives walked into a horror movie come to life the other night. This is an unbelievable scene.

'Understand, some of these are 200 years old. Some obviously much newer... It's going to be quite some time before we have a final answer.'

Some of the remains were hundreds of years old, Rouse said, while others belonged to infants believed to have been just months old when they died.

At least one of the corpses was found with a pacemaker, authorities added.

'I grieve for those who are upset by this, who are going through it, who are trying to figure out if it is, in fact, their loved one or their child — because we found remains that we believe to be months-old infants — among the those that he had collected,' Rouse said. 

'They were in various states. Some of them were hanging, as it were. Some of them were pieced together, some were just skulls on a shelf.' 

Officers said Gerlach's Tuesday night arrest culminated a monthslong investigation into break-ins at Mount Moriah Cemetery, where at least 26 mausoleums and vaults had been forced open.

Bones and skulls visible in the back seat of a car near an abandoned cemetery on Philadelphia's outskirts led police to his basement. 

He was arrested leaving the cemetery as he walked back toward his car with a crowbar, police said.

He also had a burlap bag in which officers found the mummified remains of two small children, three skulls and other bones.

Gerlach told investigators he took about 30 sets of human remains and showed them the graves he stole from, police said.

He was charged with 100 counts each of abuse of a corpse and receiving stolen property, along with multiple counts of desecrating a public monument, desecrating a venerated object, desecrating a historic burial place, burglary, trespassing and theft.

He has also been charged with criminal mischief and is being held on $1 million bond. No lawyer was listed in court records.

Police alleged Gerlach targeted mausoleums and underground vaults at the 1855 cemetery.

He was allegedly part of a Facebook group titled 'Human Bones and Skull Selling Group.' In the group, he had reportedly been pictured with a skull, though it is unclear if he ever sold any of the remains.

Yeadon Police Chief Henry Giammarco described the case as one of the most disturbing he had seen in his career.

'Rest in peace is rest in peace, and this is definitely something that tears at your heartstrings,' Giammarco said.