Essex Police are being sued over their investigation into the death of a man in Essex.
Lee Balkwell's body was found in a cement mixer in Upminster in 2002.
In 2012, an Independent Police Complaints Commission (IPCC) report described the force's investigation as 'seriously flawed'.
Mr Balkwell's parents are now claiming damages under the Human Rights Act.
They says their rights, under Article 2 of the European Convention on Human Rights, were violated by Essex Police's failures over 8 years to conduct a proper investigation into Lee's death.
They say Essex Police's assumption that he died in an industrial accident meant officers missed chances to find vital evidence and potential witnesses.
The initial investigation into Lee's death lasted just 19 days, after which Essex Police concluded he died in a tragic accident.
Between 2003 and 2010 the force reviewed the case twice, both times they found the death accidental.
At his inquest in 2008, a verdict of unlawful killing by gross negligence was recorded.
The IPCC report in 2012 upheld a number of complaints against Essex Police including their failure to secure potential evidence, failure to obtain witness statements and a failure to treat Lee's death with an open mind.
– Lee's father Les Balkwell, speaking in 2012
We don't want letters, I don't want apologies, I just want some honest police officers to go out and challenge the people that need challenging because they've never been challenged, they've never been challenged on what they said happened that night and when you analyse it, it beggars belief what's been accepted."
Essex Police have confirmed that they have received notification of the legal action.