Killer Liam Whitnell posted photos on the internet boasting about his 31st birthday celebrations behind bars which have shocked the family of his victim.

Whitnell and three others stabbed 24-year old Kowshar Hussain to death at Stepney in London’s East End in front of his terrified young wife and sister in April, 2011. He was jailed last year after a retrial.

Kowshar’s sister Amirun, 24, complained to a national newspaper after seeing the Facebook boast that “Whitnell gets to see his family when they come to visit him—but he took something from us that we will never get back”.

Mr Hussain was stabbed nine times in revenge for a “trivial incident” in Jamaica Street involving someone else.

The attackers knew he had not been involved “but was killed anyway”, an Old Bailey Judge said. An innocent man was “mindlessly murdered in revenge for a trivial incident in which he played no part.”

Whitnell is serving 24 years at Wandsworth. An investigation has been started by prison authorities into how he got access to social media, which is banned for inmates.