The owner of the house was arrested along with his servant on suspicion of kidnapping, rape and murder. They have not been charged.
The Central Bureau of Investigation (CBI) said in a statement on Monday: "Biomaterials packed in more than 40 polythene bags have been recovered from the drain in front of the house of the accused persons.
"In addition, pieces of human bones have been recovered ... the seized materials have been sent to the laboratory for post mortem, individualisation and DNA extraction."
The investigation into the murders was taken over by the CBI five days ago after local police were accused by parents of ignoring reports about their missing children - some of whom disappeared more than two years ago.
Six policemen have been sacked and three suspended, accused of negligence in handling the case.
Laurence Lee, Al Jazeera'a correspondent on the scene on Tuesday, reported that screens have only just been put up around the crime scene.
Lee said: "It has taken three weeks to put up the screens which raises huge questions about how well the crime scene has been protected."
The CBI said since taking over, they had registered 19 cases relating to the kidnapping, rape and murder of children and women. Some 41 people have been reported missing from the area.
All of the victims and those still reported missing come from impoverished families, many of whom are migrant labourers, who say their complaints by police were not taken seriously because they are poor.
|Parents of the missing children protest next to |
the crime scene after police failed to protect it
A local woman speaking to Al Jazeera said that she believed that there must be more than 500 victims.
"It must be more than 500. If they clean this gutter they'll find many more," she said.
CBI officials were cautious to suggest that the new discovery meant the death toll from killings suspected to have been committed over the past two to three years was higher.
A CBI official, who refused to be named, said: "It's difficult for us to say that the new find means there are more people that have been murdered as the parts could belong to the 19 cases already known about.
"We can't say for sure until all the DNA and forensic tests have been made."
Over the past few days, CBI forensic teams have been inspecting in and around the lavish two-storey house and excavators have been digging up drains where investigators believe the majority of the cut up bodies were stuffed.
The CBI said forensic tests of all the skeletal remains discovered would help link them to the missing people and that relatives of the missing and other connected witnesses were being questioned to establish the sequence of events.