A teenager accused of murdering 15-year-old Farnham schoolboy Luis Guembes claimed he tried to break up a fight before fleeing the scene, a jury has heard.

On the third day of the murder trial at Guildford Crown Court on Wednesday, October 21, prosecutor Julian Evans KC read out a prepared statement given to police by one of the two defendants following Luis's death in Stoke Park, Guildford, on January 19.

The defendant, who cannot be named for legal reasons, claimed he had been asked by the other teenager to keep watch while he attempted to take a mobile phone from Luis.

"I know [the other defendant], we attend the same school. I do not know Luis whatsoever," he said in the statement.

He described how the other defendant had contacted him and asked him to come to his flat.

"He said there is a guy, he owes me a phone. I'm going to take his phone tonight. I just need you to keep watch."

The teenager said he travelled to the flat on his electric bicycle before being left at the Wild Wood area of Stoke Park while the other defendant went into Guildford town centre.

He claimed the second defendant subsequently returned with someone he now believed to have been Luis.

According to his statement, a fight broke out between Luis and the other defendant.

"I saw Luis overpower [the other defendant] and begin to punch [him] repeatedly. I grabbed Luis's arm to stop the fight. Luis stood up and turned on me."

The teenager claimed he fled when Luis attempted to punch him.

"As Luis swung a punch at me, I ran off into the darkness. I grabbed my e-bike and rode off."

He said he subsequently heard someone shouting: "I'm bleeding, I'm bleeding", but could not identify whose voice it was.

The defendant denied seeing a weapon or witnessing anyone being injured beyond punches being thrown. He also denied any involvement in Luis's death.

The court heard that the second defendant, when interviewed by police, confirmed his home address and provided the PIN for his mobile phone but otherwise answered "no comment" to questions.

The jury was also shown photographs of items recovered during police searches, including a Morakniv knife in a black sheath found in bushes outside the second defendant's home.

Detective Constable Rob Franklin, the officer involved in the investigation, became the first witness to give evidence during the trial.

He was questioned by Mr Evans about CCTV footage, video recordings, Snapchat messages and telephone calls involving Luis and the defendants.

The jury also heard findings from forensic scientist Claire Morse concerning blood evidence recovered during the investigation.

In relation to the first defendant, the absence of blood attributable to Luis on clothing, footwear and a bag recovered from his home, as well as samples taken from the property, could indicate that he was not present when Luis was injured and bleeding.

However, the scientist said it remained possible that he had been present during the attack, or had been involved in injuring Luis, without blood being transferred to his clothing or other belongings.

The court heard that the forensic findings concerning the first defendant's possible involvement in the assault were therefore inconclusive.

In contrast, blood evidence recovered from clothing and footwear associated with the second defendant, as well as blood attributable to Luis found at his home, could be explained if he had been involved in the assault.

However, Ms Morse said there could be other explanations for those findings, including that the second defendant had scuffled with Luis but had not stabbed him.

The prosecution alleges that the two defendants acted together in the attack that led to Luis's death.

Both teenagers, now aged 16, deny murder.

The trial continues.