Former principal James Carragher was jailed for 14 years
Humberside Police has been criticised by a watchdog for how it handled claims of sex abuse at a children's home.
Former principal Father James Carragher, of St William's Community Home in Market Weighton, was jailed in 2004 for abusing boys in his care.
The Independent Police Complaints Commission (IPCC) started an inquiry in 2005 after cases of others accused of abuse at the home collapsed.
The assistant chief constable said it would have been handled better today.
Humberside Police started Operation Aldgate in 2001 which focused on alleged child abuse between 1965 and 1992 at the children's home.
The home was run by the Catholic De La Salle teaching order to provide residential care and education for emotionally and behaviourally disturbed boys aged from 11 to 18.
The inquiry led to Carragher being jailed for 14 years after a trial at Sheffield Crown Court.
Another five men were charged with indecent assault. But during trial two were acquitted while three had their cases dropped.
Complaints were then made by individuals who had been subject to the police inquiry and the matter was referred to the IPCC.
The watchdog looked into 120 complaints made by nine different people.
Of those, 25 were substantiated, six were partly substantiated and 80 were unsubstantiated. A further nine could not be proved or disproved.
The report highlighted a number of failings in the inquiry.
It found there "was a lack of resources and funding to ensure a robust investigation was undertaken".
In addition, there "was a failure to pursue reasonable lines of inquiry" and an "inconsistent approach on the arrest of individuals".
Nicholas Long, IPCC commissioner for Yorkshire and Humberside, said: "The investigation has found the majority of the complaints to be unproven, but it is clear there were failings in the investigation.
"Some of these appear to have been due to the failure to pursue lines of inquiry, compounded by lack of staff and resources."
Mr Long added: "There are no winners in this matter. Lives have been ruined - either due to the abuse that has been proven to have taken place or due to innocent people being the subject of an intense investigation."
Alan Lever, assistant chief constable of Humberside Police, said the investigation at the time was not a priority for the force.
"We were juggling other matters, other priorities which were regarded as more important.
"So this inquiry and the staffing of it, I have to say back in 2001, this was not seen as a major priority for Humberside Police and that's why it was staffed the way it was."
Mr Lever said he accepted the criticism adding: "If we had an inquiry such as this today it would be handled in an entirely different way."