The Central Bureau of Investigation may not have got the weapon used in the brutal murder of teenaged girl Aarushi and domestic help Hemraj, but it ended up helping the Noida residents in cleaning the drain.

Taking a cue from the Nithari serial killings, the CBI on Friday hired sweepers on contract to clean the drains around the residence of the Talwar's, located in Sector 25 of Noida, in search of the murder weapon.

While success continued to elude the CBI in making any breakthrough or recovering the murder weapon, the drains around the area, which were possibly not cleared for several months, were finally cleaned.

Suspecting that the weapon could be thrown somewhere near the Talwar house, the CBI engaged people to get drains cleaned, searched bushes and garbage dumps in areas surrounding the dentist's residence.

The cleaning of drains had come as a big help to the CBI in the Nithari serial killings, where they recovered human ones and skeletal remains.

CBI also questioned some of the Noida police officials in connection with the murder weapon, the sources said, adding, after all the agency would like to know as to what efforts were made by the police in recovering the same.

The forensic teams were also trying to conclusively establish the weapon used.