One of the brothers accused of killing traffic head constable Vilas Shinde was remanded in judicial custody on Tuesday, as the Khar police did not seek further custody.
The 20-year-old accused will be at the Arthur Road jail till September 20.
The police said an identification parade will be conducted, and that they have at least five eye witnesses.
The accused was in judicial custody when the police charged him for attempt to murder.
But when Shinde died of his injuries on September 1, the accused was arrested on murder charges, produced in court the next day and sent to police custody till Tuesday.
The Khar police said they have a “watertight” case against the accused and his 17-year-old brother.
They are also seeking the permission of the Juvenile Justice Board to try the minor as an adult under the new juvenile justice act.
Shinde was attacked on August 23 at a petrol pump near Rajasthan hotel on SV Road.
He was collecting personal details of motorists as part of an e-challan programme, when he stopped the minor, who was driving a bike.
He asked him to call his parents, as the boy was not legally allowed to drive.
The minor called his brother and is said to have exaggerated the incident.
This enraged the accused, who reached the spot and attacked Shinde with a wooden stick on the back of his head.
He was arrested the next day from Belapur and his brother continues to stay at the correction home.
Shine died of his injuries nine days after the incident, at the ICU of Lilavati Hospital.