Philadelphia Police say a pimp and two prostitutes killed a Northeast Philadelphia man, chopped up his body and tossed it into the Schuylkill River after a botched robbery.

Keith Tolbert, Angel Weston and Stephenie Foulke were charged Thursday with the murder of Frank Zarzycki, police said.

Zarzycki's torso was found by fishermen near the 1300 block of Schuylkill Avenue in the Grays Ferry section of Philadelphia around 8 a.m. Tuesday morning. The 40-year-old's head, arms and legs had been chopped off and were missing.

Using a distinctive tattoo on Zarzycki's upper back, investigators on Wednesday were able to identify the man who had been reported missing by family a week before.

Philadelphia Police Homicide Unit Capt. James Clark said Zarzycki, who lived in the Somerton section of the city, went to Apartment 26 inside 220 South 11th Street last Monday, August 26 to have a sexual encounter with prostitutes.

The man allegedly began a sexual act with Weston, 21, and Foulke, 22, in the second-floor apartment's living room when Tolbert, the 34-year-old alleged pimp, came in to rob Zarzycki.

During the struggle, Zarzycki was beaten, tasered and then suffocated. He died as a result of the fight.

Capt. Clark said investigators believe the trio panicked and dragged the man's lifeless body to the bathroom. There, Tolbert allegedly used a hatchet to dismember Zarzycki.

His torso was then placed into a bag and thrown into the river, police said.

Investigators are still searching for Zarzycki's other body parts and are leaning on the suspects to share where and how they were disposed.

"We're still talking to them," Capt. Clark said of the suspects. "We have detectives back out at the scene. We will probably still have the Marine Unit go back out to certain locations along the river. The investigation is still on going."

The trio were arrested on Saturday, before Zarzycki's body was found, after the department's Vice Unit held a sting at the apartment.

The housing unit, which is listed in Tolbert's name, is located in Center City, just south of busy Market East near the campus of Thomas Jefferson University Hospital. The apartment building has a mix of Section 8 and mixed-income units inside. Investigators say Tolbert paid only $30 a month in rent to live there.

Capt. Clark said the home was a known prostitution spot and that phone and computer records showed the victim had frequented the place.

"My understanding is he had been there before and obviously he wasn't robbed, but for whatever reason, this time they chose to rob him and it escalated to him being killed," Capt. Clark said.

Neighbors who live in the apartment building tell NBC10.com they saw plain clothed officers visit the same apartment last week and arrest a man and woman for alleged prostitution.

Since then, a police officer had been guarding the apartment, neighbors say. Investigators then came back to apartment on Wednesday to collect evidence.

Capt. Clark said crime scene investigators were back out at the apartment on Thursday to search for additional evidence.

Sources close to the investigation tell NBC10 crime scene techs found large pieces of flesh inside a bathtub drain pipe. That pipe was removed and taken into evidence.

NBC10 visited Zarzycki's family in Northeast Philadelphia on Thursday, but they did not want to speak with the media.

Tolbert, Weston and Foulke have been charged with murder, robbery and related offenses and all, police say, have criminal histories.

Keith Tolbert (L) and Angel Weston (R) pictured. A mugshot for Stephenie Foulke was not available.

Frank Zarzycki pictured in this undated photo.

Contact Vince Lattanzio at 610.668.5532, vince.lattanzio@nbcuni.com or follow @VinceLattanzio on Twitter.