Nigeria, Jan. 6 -- It was about two weeks after John Anozie buried his mother in Bende Local Government Area of Abia State, south-east Nigeria, and returned to Lagos to be with his wife, Nnenna Anozie, and their four children, the eldest of whom was less than nine years old at the time.

On the quiet morning of 15 June 2017, just before 8 a.m., Mr Anozie was set to drive out of their compound. As the security guard flung the gate open for him to hit the road, five armed men in mufti stormed in with their guns drawn.

"One of them glanced through his phone, as if checking the photo of his prey, and confirmed their target," Mrs Anozie recalled.

The men, later identified as operatives of the now-defunct Special Anti-Robbery Squad (SARS) of ...