This afternoon the jury heard that Mercer - wearing a black shirt in the glass sealed dock - went to the house of a friend after the killing.

From the house, that of 16-year-old Boy M who cannot be identified, Mercer used the teenager’s mobile to make several phone calls.

Boy M faces three counts of assisting an offender.

Shortly after 7.30pm James Yates, 20, of Dodman Road, Croxteth, and a 17-year-old, Boy Q, arrived at the house.

Yates denies two counts of assisting an offender and possessing a gun.

Boy Q denies two counts of assisting an offender.

Mr Flewitt said a crucial witness in the case, who cannot be identified, was summoned by Mercer to Boy M’s house.

There the alleged killer handed the special witness a red and white bag containing the murder weapon, said Mr Flewitt.

As he left the house, Mercer called after him: “Don’t say nothing to no-one. Ring me when you get in,” said Mr Flewitt.

“Although the package felt heavy he did not immediately appreciate what was in it.

“However, on his way home in the taxi, he felt it in his pocket and and realised it was a gun.

“As soon as he got home, he went into the back garden and hid the package in the dog kennel, where it remained for the next few days.”

Four days later, Boy K, aged 17, who is charged with possession of two guns, ammunition and assisting an offender, arrived at the witness’s house to move the murder weapon into the loft.

Police found the murder gun on 30 September - along with an imitation Walther PPK pistol and a bundle of ammunition.

Mr Flewitt told the jury that the special witness was arrested on October 6 when he returned home from a holiday in Florida.

Detectives considered charging him with a number of offences but it was decided to offer him immunity from prosecution providing he gave a truthful account of the circumstances surrounding Rhys’s murder.

Mr Flewitt said: “He has accepted those terms and has entered into an Immunity Agreement with the Crown Prosecution Service.”

He added that the defence could suggest he was complying to “save his own skin”.

He added: “But you will also have to bear in mind that he first gave his account of events in a police interview long before he was offered immunity from prosecution and, in any event, there is independent evidence” to support his evidence.

The trial will resume at 10am tomorrow.