Yoo Byung-un, 73, had been the target of South Korea’s largest manhunt, after the 16 April sinking of the MV Sewol, which capsized on a trip from Incheon to the holiday island of Jeju.
Of the 476 passengers and crew, 339 were children and teachers from the same school near Seoul. Only 172 were rescued; the remaining 304 drowned.
The police chief in charge of the case in the southern city of Suncheon was sacked on Tuesday for failing to recognise the book’s significance after the body was found on 12 June.
The book – Greater Love has No One Than This – was written in 1995 while Mr Yoo was serving four years in jail for fraud.
An empty bottle of a shark-liver-oil health tonic, made by his family company, and three empty bottles of alcohol were also found near his body.
Media reports said his head had separated from his torso, which police said may have been due to decomposition.
Two attempts were made to take fingerprints, with all the digits of the left hand cut off to allow this. Finally a print from a right index finger, taken from the refrigerated body, matched one on file. Identification was confirmed by DNA tests.
Police said Mr Yoo’s death did not appear to have been the result of foul play. More tests are under way to establish a cause.
Mr Yoo headed the family that owned the operator of the ferry that capsized in South Korea’s worst maritime disaster in 20 years. It was claimed the crew were untrained, and the ship had been modified to carry more cargo, making it top-heavy and liable to topple. Alleged bribery is being investigated.
Failure to find Mr Yoo had become a political headache for the president, Park Geun-hye, whose government faced heavy criticism over the disaster.
The Sewol’s 15 surviving crew members, including the captain, are on trial on charges ranging from homicide to negligence, accused of abandoning ship while children were told to stay in their cabins.
Mr Yoo, also a photographer and co-founder of a church which made organic ice cream, was accused of embezzlement, negligence and tax evasion.
Authorities had offered a reward of about £300,000 for information leading to his arrest and detained family members.
The time of death was unclear as the body had decayed by more than 80 per cent. It was found about a mile from a retreat police raided on 25 May after a tip-off he was there.
The announcement came less than 24 hours after prosecutors apologised for failing to capture Mr Yoo when they released interim results of their investigation into the disaster.
They made no mention on Monday that a body suspected of being his had been found.
A court also issued a fresh arrest warrant for Mr Yoo.
The Yoo family business remains under investigation. His sons, Yoo Dae-gyun and US-based Yoo Hyuck-ki, were majority owners of the shipping company Chonghaejin Marine Co Ltd through an investment vehicle and had stakes in nine affiliates connected to the Sewol.
In the hunt for Mr Yoo, police searched premises belonging to his Evangelical Baptist Church and arrested church members.