A man convicted of manslaughter over the death of PC Andrew Harper has lodged an appeal against his sentence.
The police officer sustained catastrophic injuries when he was dragged behind a getaway car driven by Henry Long in Berkshire last August.
Long, 19, has now lodged an application with the Court of Appeal to challenge his 16-year jail sentence.
PC Harper’s mother said hearing about the appeal was “another kick in the stomach that leaves us feeling awful”.
PC Harper, 28, from Wallingford, Oxfordshire, had been married for a month when he died on 15 August last year.
Long, who was driving the vehicle, pleaded guilty to manslaughter but was acquitted of murder following a trial at the the Old Bailey along with his passengers Albert Bowers and Jessie Cole.
Their sentences have been referred to the Court of Appeal after the attorney general considered them to be “unduly lenient”.
Debbie Adlam, PC Harper’s mother, said: “My family and I totally respect anyone’s right to appeal against their sentence. We live in a fair society.
“However, this news, coming as it does on the very last day that he had to put in his appeal, is simply another kick in the stomach that leaves us all feeling awful.
“We will recover from this as we have to do but my thoughts today are absolutely with my heroic son who gave his life trying to protect others and those responsible for his loss will not live rent free in my head.”
PC Harper’s wife, Lissie, said: “This update comes as no surprise to me following news that two of them are also seeking leave to appeal against their conviction.
“None of Andrew’s killers have shown any remorse. So this is just carrying on the way that they are and have been throughout the past year.
“It is upsetting – but just helps to drive my determination with my campaign calling for Harper’s Law.”
Albert Bowers and Jessie Cole, both 18, had already lodged appeal applications against their 13-year sentences and manslaughter convictions.
No date has been set for the appeals to be heard.
Earlier on Friday, Mrs Harper, 29, said she was “horrified” by reports that her husband’s killers had received £465,000 in legal aid.
Mrs Harper is campaigning for Harper’s Law to ensure those who kill emergency workers are jailed for life.