A teenager told police he watched in horror as a man was battered to death with baseball bats.
Jason Jackson said: "I felt sick, horrified and scared about what happened. It was disgusting."
Divorcee Gary Rae died from horrific injuries after he was allegedly attacked by a gang of six teenagers outside his Hailsham flat.
Jackson, 18, and two others gave themselves up the day after the father-of-two was murdered. A jury at Hove Crown Court heard that he was upset and in tears when detectives first tried to interview him.
He sat with his head in his hands for most of the time as he answered questions during later interviews.
Jackson told officers he had been to a party at Shane Challice's flat in South Street on May 29 last year.
He said William Devall had turned up with a baseball bat and told them he wanted to scare Mr Rae.
Jackson said he thought Devall was trying to act big and did not think he was going to attack Mr Rae.
He added: "William said he wanted Mr Rae out of Hailsham that night and that he was going to cripple him. After a while William stood up and said: 'let's go.'"
Jackson told officers Devall left and he, Challice and two juveniles followed him to Mr Rae's flat in High Street. He said: "When we got there William instructed us where to stand and told one of the others to knock on the door. He knocked and called to Gary to come down and when there was no answer William banged on the door with the bat.
"When Mr Rae answered the door William stepped out from behind the wall and hit him with the bat.
"William was standing over him hitting him with the bat six or seven times.
"One of the others hit him twice across the back of his legs with a bat. I felt sickened and shocked. I was under the impression he was just going to scare Gary.
"As we turned and walked away I heard William say, 'that is for going near Amy'."
It is alleged that Devall organised the attack because he was jealous of ex-girlfriend Amy Heaseman visiting Mr Rae's flat with other teenagers.
Jackson said that after the beating Devall and a 17-year-old juvenile hid their bats in a bush at Black Path.
Jackson said he and some of the group, including Challice and the juvenile who had used one of the bats, later went back for them.
He said the bats were taken back to Challice's flat and hidden before they were taken away in the early hours by Devall's brother Aaron.
He told detectives that he had not taken part in the assault on Mr Rae. But he said nobody had tried to stop it happening or tried to help Mr Rae afterwards.
Devall, 19, of Meadow Road, Hailsham, and a 17-year-old who cannot be named for legal reasons deny murder but admit manslaughter on the grounds of diminished responsibility.
Jackson, of Albert Road, Polegate, Challice, 19, and two juveniles aged 16 and 17 deny murder.
The trial continues.
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