Detectives hunting the killers of Pc Sharon Beshenivsky have said they have received a number of calls after naming their three prime suspects.
The 38-year-old officer was shot dead during an armed raid at a travel agency in Bradford on Friday 18 November.
The suspects are Muzzaker Shah, 24, and brothers Mustaf Jama, 25, and Yusuf, 19. All live in London.
A West Yorkshire Police spokeswoman said some information had been received and inquiries were continuing.
Mustaf Jama and Yusaf Jama are from the north Kensington area of London.
Muzzaker Shah was born in Burnley but has lived in London since 2001.
Pc Beshenivsky was gunned down as she and a colleague, Pc Teresa Milburn, 37, went to investigate a robbery at the travel agency in Morley Street.
Pc Milburn suffered a gunshot wound to the shoulder.
On Saturday the police spokeswoman said detectives had received "a number of calls" regarding Friday's appeal and again urged the public to get in touch.
Det Supt Andy Brennan, who is leading the hunt for the killers, said on Friday: "I believe the men who committed this crime are very dangerous. They were already known to police."
He told reporters at a briefing in Bradford there was no indication any of the three suspects had left the country.