The family of a cyclist who was killed in collision with a lorry have written to Kent Police demanding to see the driver’s blood tests.

Mark Dunk was 28 in February 2010 when the fatal collision took place, as he cycled to work in Thanet, Kent. His family say they “can’t come terms with” the investigation into his death after police admitted failing to fully investigate the death following a case review.

The CTC says the family's response is understandable, given the circumstances, and the case demonstrates why families should be kept informed during police investigations.

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Mr Dunk’s mother, Christine Elson, wrote a letter to chief constable, Alan Pughsley, and made a complaint to the police watchdog.

She writes: “"We want to know what was in [the lorry driver's] system. It should have been divulged to us and the public at large at the inquest.

"I've really come to terms with losing my son, but I can't come to terms with the investigation into his death.

"All I want out of this is justice for my son and the truth because he's not here to defend himself."

Although the initial police investigation concluded Mr Dunk cycled into the path of the lorry, recording a verdict of accidental death, the family disputed this. Following a campaign by the family Kent Police carried out a serious case review, with Essex Police, and found there were “missed opportunities”, which included a failure to examine the driver’s “consumption of codeine and its effects on him”.

Mrs Elson says she has lodged a new complaint with the Independent Police Complaints Commission (IPCC).

Legal driving limits for drugs such as codeine were only introduced last year. Prior to that police officers had to assess whether a driver was capable of driving without set guidelines being in place.

CTC the national cycling charity's Road Safety and Legal Campaigns Officer, Duncan Dollimore, told road.cc: "This case demonstrates the difficulties that can arise when the families of victims are not kept fully informed about the progress of police investigations.

"It may well be that the driver’s blood test results show nothing of any relevance, but when, as the police have already admitted in this case, there have been other failings in the investigation, it is understandable that Mark Dunk’s family will wonder whether anything else was missed. If more information had been provided to them at the time perhaps they would not be having to ask these questions five years after their son’s tragic death."