The man, known as David, said he wanted answers about how Lincolnshire Police dealt with allegations against Gordon Dawson, a farmer from Spilsby.
Mr Dawson shot himself in 2007 after officers informed him of the inquiry.
In a statement, Lincolnshire Police said "procedures were correctly followed at the time" but policy has subsequently changed.
David claimed Mr Dawson had repeatedly abused him from the age of 15.
According to Lincolnshire Police, the first allegation was made in 1999 but no action was taken due to "insufficient evidence".
In 2006 police arrested Mr Dawson after four other men came forward claiming they were also abused as children between 1964 and 1986.
In early 2007 another alleged victim came forward.
An investigating officer phoned Mr Dawson on 23 March 2007 to tell him he would be questioned further and a few hours later he was found dead at his home.
Following Mr Dawson's death the investigation was dropped but David later complained to the police about the way the investigation was handled.
Speaking on the BBC's Victoria Derbyshire programme, David said: "We've had no justice, no finals, no process.
"It's been shutdown, shutdown all the way. I just want some answers."
Supt Rick Hatton said: "We have revisited the circumstances surrounding the investigation into Mr Dawson and are satisfied that the investigation that took place was thorough and robust, and no misconduct took place.
"However, a number of lessons were learned in relation to best practice and fed back to the Public Protection Unit.
"We are very sympathetic to the position of the victims in this case and appreciate they may feel that Mr Dawson was not brought to justice."
The force said any similar situation today "would see Mr Dawson's guns removed from him as policy is now quite different".
Police have denied mishandling a sexual abuse investigation which left a victim claiming he had been denied justice.