Mr Causer's sexuality was the motove for the attack, prosecutors claim
A gay teenager was battered to death in a homophobic attack by a man armed with a hardback history book, a court heard.
Gavin Alker shouted homophobic abuse at Michael Causer, 18, as he punched and kicked him at a house in Huyton, Merseyside, on 25 July 2008.
Liverpool Crown Court was told he did not know Mr Causer and started the attack after finding out he was gay.
The 19-year-old, of Fleetwood Walk, Runcorn, denies murder. Another man has already pleaded guilty to the charge.
The jury was told Mr Causer had been out drinking with friends when they decided to go to a house in Biglands Drive belonging to the grandmother of Michael Binsteed.
Among the group was James O'Connor, 19, of The Clough, The Brow, Runcorn, who pleaded guilty to murder last month.
Binsteed, 18, of Evelyn Avenue, Prescot, defended Mr Causer but tried to cover up the attack and pleaded guilty to perverting the course of justice.
Although the three were friends the atmosphere in the house changed when O'Connor's friend Mr Alker arrived, said Richard Pratt QC, prosecuting.
The barrister said: "There is, we say, an important fact in this case and indeed one which lies at the heart of it. Michael Causer was gay.
"As he was subjected to the attack which would ultimately kill him, Gavin Alker was heard to abuse him using anti-gay language, indicating clearly that Michael Causer was being attacked, and was killed, because he was gay."
Mr Causer, of Whiston, Merseyside, was asleep upstairs when he was attacked by Mr Alker three times, the court was told.
During the first attack, the prosecution claimed Mr Alker, a student, used a hardback American history book to hit Mr Causer around the head.
Mr Pratt told the court: "Alker showed no sign of remorse or concern for Michael Causer.
"Quite the opposite, he used a cigarette lighter to burn hairs on Michael Causer's leg and picked up a knife and threatened to rip his body piercings out."
Mr Alker, O'Connor and Binsteed decided to dump Mr Causer in the street nearby by carrying him over a fence, Mr Pratt said.
Binsteed later called an ambulance after seeing Mr Causer bleeding profusely from the nose and mouth, but told police the victim was attacked in the street by three random men.
Mr Causer was taken to Whiston Hospital but transferred to Walton's neurological centre with massive head injuries. He died on 2 August.
A post-mortem examination showed multiple face fractures with extensive haemorrhaging and neck bruises.
In a police interview, Mr Alker's solicitor read a prepared statement in which he blamed Binsteed and O'Connor for the serious assault.
The case continues.