FBI, Philly police dig up Horsch backyard at home tied to 7 missing women in possible serial killer probe

Police and the FBI have returned to dig up the backyard of a Philadelphia home as part of an ongoing investigation into a potential serial killer that has already turned up apparent "snuff" films, ash-filled urns and evidence linked to at least seven missing women .

Images show an excavator in the backyard as police in protective gear continue to come and go from the property this week.

They've set up tents in the backyard and out front and covered parts of the lawn in tarps.

Investigators could be seen wearing various levels of safety equipment, including face masks, hazmat suits, rubber gloves, protective sleeves and booties.

One crime scene investigator was seen wearing what appeared to be a chemical-spraying backpack as she entered the property.

A crime scene photographer also came and went Wednesday.

HAZMAT CREW REMOVES 'GLASS VIALS,' VACUUM FROM HOME LINKED TO MISSING WOMEN IN POTENTIAL SERIAL KILLER PROBE There is yellow police tape around the perimeter, and uniformed officers are standing watch.

Joseph Giacalone, a retired NYPD cold case sergeant and adjunct professor at the John Jay College of Criminal Justice, said the scale of the investigation stands out to him.

"The sheer number of crime scene technicians that are going in and out of this house — usually you try to keep it to a minimum because you don't want people trampling on things and stuff like that," he told Fox News Digital.

"I just think that there's so many different nooks and crannies that they have to cover that they need this many people.

So, I mean, we're not talking three or four, we're talking 10, 12, or 14 people going in and out of this place at one time." Police have repeatedly visited the home in recent weeks, carrying out boxes of evidence earlier this month, including one marked " glass vials ." A Philadelphia Police Department spokesperson declined to go into specifics about the continued searches Thursday, citing the active and ongoing investigation.

PHILLY SERIAL KILLER PROBE COULD EXPOSE LARGER NETWORK BEHIND APPARENT 'SNUFF' FILMS, EXPERT SAYS "Investigators continue to examine evidence and pursue all available leads," she told Fox News Digital.

"At this time, we are unable to provide specific details regarding investigative activities at the property, any potential findings, or the status of efforts to authenticate the previously recovered images and videos." Raymond "RC" Horsch , a producer of BDSM-themed pornography and books, died last year at 82.

However, police searched his former home after arresting his 44-year-old son Eugene Horsch in June.