The mother of a 15-year-old boy who was murdered on a family fun day out a month ago has spoken of her “emptiness and heartbreak” as police appeal for help in finding his killer.

Rene Graham was killed in Emslie Horniman’s Pleasance Park in Ladbroke Grove, west London, at about 7.20pm on July 21.

His mother, Janay John-Francois, has now asked for help after Rene was shot in the crowded park.

In a statement released through the Metropolitan Police, she said: “I cannot begin to describe the depth of my pain after losing my precious angel.

This is a grief so profound I would not wish it upon my worst enemy

“The emptiness and heartbreak, there are no words that can capture the agony of my loss.

“This is a grief so profound I would not wish it upon my worst enemy – I’ve lost everything, my world will never be the same.”

She begged people who may know “anything at all – or witnessed anything” to come forward, saying “your bravery could be the key to bringing peace to a broken family”.

From the depths of my shattered heart I implore you to please come forward and help me find justice for my son Rene Graham

In a personal plea, she added: “Today is my son, but tomorrow could be one of yours. Please stand with me through the darkest of times.

“From the depths of my shattered heart I implore you to please come forward and help me find justice for my son Rene Graham.”

Four men – two aged 21 and the others aged 20 and 25 – who were arrested on suspicion of murder, have since been released with no further action.

Detective Inspector Adam Clifton said Rene was “murdered in a park that was filled with people” and “the shooter was noticeable in that he was very warmly dressed for such a hot day, all in grey with a waterproof jacket, cap and a balaclava”.

Police believe someone may have seen Rene in the park before he was shot, or perhaps have pictures or footage from that day that may have him, or the suspect, in the background.

Mr Clifton said: “We urgently need to understand the exact sequence of events in the park and it is clear many more people saw the shooting than have come forward. It is those people I am appealing to today.

“Please tell us what you saw, no matter how small or insignificant you may think it is, please contact us.

“Similarly, we are keen to hear from anyone who saw someone acting suspiciously on the towpath, either before or after the shooting.”