Two more people including a 15-year-old boy have been arrested over the death of an ex-Royal Navy officer thought to have been run over by his own car.
Mike Samwell, 35, was fatally injured as he tried to prevent thieves from stealing his car from outside his home in Chorlton, Manchester, on Sunday.
A man, 29, and teenager, both from south Manchester, are being held on suspicion of murder and burglary.
Two men aged 20 and 21 previously arrested have been released on bail.
Mr Samwell was asleep with his wife Jessica in their Cranbourne Road home when they were awoken by a noise outside and he went to investigate.
Police believe he was run over by his car, a black Audi S3, which was taken and later found about three miles away on Whitby Avenue, Ladybarn, with extensive damage.
Mr Samwell’s family described him as a “special, kind and exceptionally talented man”.
Det Insp Lewis Hughes of Greater Manchester Police said: “This has been a fast-moving investigation and we have made significant progress since Mike’s murder and have now arrested two more people who will be questioned by detectives later today.
“However, our inquiries do not end there and we will continue to move forward with the investigation but we still need the public’s help.”
He urged anyone with information to contact police immediately.