Joseph Nwabuko may have been trying to note a number plate

Joseph Nwabuko was shot on Monday after an ambush at the Nationwide Building Society in Birmingham.

Police say he may have been killed for trying to write down the getaway car's registration.

Joseph's older brother Johnson said; "These guys are vicious. They had the money there was no need for it. They have got to come to justice."

�150,000 reward

He added: "My brother was a nice guy, he wouldn't hurt anybody and for this to happen to him in such a vicious way, it hurt.

"The most I can say is, it was just curiosity, he saw something that did not look right."

The 28-year-old had moved to Birmingham from Walsall two weeks ago.

Securicor has offered a �100,000 reward for information leading to the conviction of the robbers and the Nationwide another �50,000.

Detectives investigating his murder have been examining extensive CCTV footage of the murder scene.

A post-mortem examination showed Mr Nwabuko died from a gunshot wound to the chest, after a round passed through his left arm and into his lungs.