The accused, identified as Indushekhar, allegedly killed the seven victims and dumped their bodies at different locations. Police have so far recovered the body of a child.
Wife allegedly murdered first
The alleged killings took place in a residential neighbourhood on 59th Cross, near Basroom Circle, under the jurisdiction of Rajajinagar Police Station.
According to reports, Indushekhar first allegedly murdered his wife using a grinding stone. He then wrapped her body in a cloth and dumped it near Nandi Hills.
To evade suspicion, he allegedly switched off his wife's mobile phone and told neighbours that she had gone on a trip.
Six in-laws allegedly killed
The cab driver subsequently allegedly murdered his mother-in-law, two brothers-in-law, their wives and his seven-year-old nephew.
The incident came to light after the mother of one of his sisters-in-law lodged a missing complaint with the police.
Police seize car and murder weapon
Police have seized the car allegedly used to transport the bodies, along with the grinding stone believed to have been used to kill his wife.
Investigators suspect that Indushekhar used chemicals to remove bloodstains and clean the house after the alleged murders.