A callous thug who murdered a rough sleeper by repeatedly dropping a paving slab on his head will spend a minimum of 25 years behind bars.

Defenceless Andrew O'Connell, 54, of Chatham, was staying in Brighton’s Royal Pavilion Gardens when the brutal and unprovoked attack took place on the night of August 7 last year.

Chilling CCTV footage shows Sergio Lemori, 33, wearing a t-shirt, shorts and flip-flops walk up to Mr O'Connell and drop the huge stone on him four times.

"Much-loved family man" Mr O'Connell wasn't found for more than seven hours and died from his injuries two days later in hospital.

Lemori, unemployed and of no fixed address, was arrested nearby the following night and charged with murder.

He originally denied the charge, despite being shown the horrendous footage, but after being judged fit to stand trial changed his plea at Lewes Crown Court last month.

Yesterday he returned to the court and was sentenced to life imprisonment, with a minimum term of 25 years.

He's never attempted to explain his actions.

In a statement, his family said: “Andrew was a family man who was loved by many.

“He was a kind, intelligent man with a free spirit who loved to travel. As a family we are utterly devastated, hurt and angry that he has been taken so cruelly from us.”

Detective Inspector Mark Woodall said: “This was a completely unprovoked attack on a vulnerable and defenceless man who was unknown to Lemori, and who was simply minding his own business as he slept rough in Brighton’s Royal Pavilion Gardens that night.

“The incident has caused a huge amount of distress to Mr O’Connell’s family, who are understandably bewildered as to how and why this tragic incident occurred.

“Lemori changed his plea to guilty – having originally denied even being in the area at the time – however he has never provided an explanation as to why he carried out the attack, which of course makes it even more difficult for the victim’s family and friends to process.

“Despite this, we are satisfied that justice has been served and one more dangerous criminal has been removed from the streets of Sussex.”

Senior Crown Prosecutor Claire Gallagher added: “The prosecution was able to put together such a strong case that the defendant pleaded guilty to murder at an early stage in the case, knowing that his DNA had been found near the scene and the murder had been captured on CCTV.

“The defendant clearly intended to kill or at least seriously injure his victim. He came armed to the scene with a weapon, in this case a piece of paving stone, and he had obviously pre-planned his attack.

“Perhaps the most sickening aspect to this case is that the victim was completely defenceless and vulnerable, given that he was asleep at the time he was attacked.”