John Stalker, who was one of Britain's most high-profile police officers, has died aged 79, his family have announced.
Mr Stalker served as an officer for more than three decades, rose to the rank of Deputy Chief Constable and led a major inquiry into policing in Northern Ireland, which became known as the Stalker Inquiry.
Mr Stalker, who is survived by his two daughters, six grandchildren and two great-grandchildren, had been in poor health following the death of his wife 14 months ago.
Colette Cartwright, his eldest daughter, led tributes to him.
She said: "Our dad John was a beloved husband, grandfather and great-grandfather who enriched the lives of many.
"After marrying my dear mum Stella in 1961 he spent his life as a devoted police officer, proudly serving the people of Greater Manchester for over 30 years.
"He is fondly remembered by many as going above and beyond the call of duty and was committed to making a difference for those most in need.
"As testament to this, he devoted his life to a career in CID where he worked for 16 years, rising to the rank of Detective Superintendent.
"Respected by many of his colleagues, he had a varied career and held posts in the Serious Crime Squad and the Bomb Squad. He also became the first head of the drugs squad.
"In 1978 - aged 38 - he was appointed head of Warwickshire CID, the youngest Detective Chief Superintendent in the country - later becoming Deputy Chief Constable of the Greater Manchester Police in 1984, the biggest police force in the provinces.
"This is something that my dad worked so hard for and we, as a family, will always be immensely proud of his accomplishments."
During his time as a police officer Mr Stalker travelled around the world studying terrorism and crime in Europe, the USA and South America and on his return he worked for two years in Northern Ireland, investigating an alleged state "shoot to kill" policy targeting members of the Provisional IRA.
After his retirement in 1987 he carved out a new career as a journalist and pursued his passion for writing, publishing an autobiography in 1988.
As a junior detective one of his roles included involvement in the notorious Moors Murders of the 1960s.
His job included developing the photographs and listening to the tape recording made by Ian Brady and Myra Hindley as three-year-old Lesley Ann Downey was murdered.
He also held posts within the Serious Crime Squad and the Bomb Squad and became head of the first drugs squad at Greater Manchester Police (GMP), where he served most of his career.
He travelled the world studying terrorism and crime in Europe, the USA and South America which led to his appointment to head an inquiry into policing in Northern Ireland.
Mr Stalker was asked to investigate the RUC shootings of six people but was removed from the inquiry shortly before it was due to report in 1986.
There was also behind-the-scenes fears that a Masonic plot within the police against Mr Stalker could be revealed during one of the most controversial episodes of the Troubles, according to newly declassified files that were released in 2016.
He was taken off the case at the moment he believed he was about to obtain an MI5 tape of one of the shootings.
Suspended over allegations of associating with criminals, he was later cleared of any wrongdoing and reinstated to his job as deputy chief constable of Greater Manchester Police but his report was never published.
The high-profile and highly controversial inquiry saw him regularly in the national spotlight.
He was just as often in the public spotlight after his retirement from the police in 1987 as he was while still a serving officer; carving out a career in the media as an expert on policing, appearing on crime-related TV shows including Crimestalker and writing his autobiography.