Harry Dunn's alleged killer has been urged to return to the UK by the mother of PC Andrew Harper, who died in the line of duty less than two weeks before the Northamptonshire teenager.
Deborah Adlam asked Anne Sacoolas, who went back to the United States claiming diplomatic immunity after the fatal, wrong-way crash last year, to 'resolve the issues'.
"This is not going to go away so please bring an end to this current situation and give Harry's family and your own a better future," she wrote in an email published on Twitter on Sunday (August 16).
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"You all deserve to live more peacefully than anyone can possibly be at the moment."
PC Harper, 28, from Wallingford, Oxfordshire, died after being dragged by a getaway car as he tried to stop three quad bike thieves near Sulhamstead, Berkshire, on August 15, 2019.
Twelve days later, Harry, 19, died in hospital after his motorcycle was hit head-on by a car being driven on the right-hand-side of the road by Sacoolas near Croughton.
While those responsible for the police officer's manslaughter have been jailed, the American mother refuses to face her charge of causing the Northampton Town FC fan's death by dangerous driving and the US will not extradite her.
The two mothers, Mrs Adlam and Charlotte Charles, have become friends as they share the 'indescribable pain' of losing their sons in tragic circumstances, hence the email to Sacoolas.
"The reason for me writing to you is to try and help you see a way forward for both you and Harry's family. There is too much suffering going on to sit and do nothing," she wrote.
Mrs Adlam described Harry's family as 'languishing, left to find a way to deal with the fact that you left without any apparent concern for those left behind to pick up the pieces'.
"Thing will inevitably get worse for them but I imagine for yourself and your family too," she adds in the email.
"You too have children, they will want to feel loved and respected as they grow, but by allowing the current situation to carry on, you risk them spending their lives in the shadow of what is happening now and how it has been handled.
"They could experience more negativity than you may have realised if things are not looked at and handled in a sensitive and decent manner for all concerned."
Mrs Charles told BBC News she was 'blown away by Debbie's love and support'.
"For another mother who is suffering as intensely as she is, her unselfish act in writing this letter just shows the power of the human spirit and how kind people in this country really are," she added.