A similar thing happened in Scotland. Willie MacRae was an SNP activist and lawyer, as well as a vocal opponent of nuclear power. He claimed to have documents proving that the UK Atomic Energy Authority planned to dump radioactive waste in the North Sea. He also claimed he was under surveillance by police Special Branch and MI5, the Security Service.
In April 1985, MacRae was discovered by passers by in his car, on an isolated moor. He had been shot once in the head. The gun was eventually found
60 feet away in a burn(river). The documents relating to the waste dumping were not found on his body or in the car. MacRae's office was burgled after his death.
Verdict: suicide