Martin Goldberg, 46, deputy head of a Southend private school, had images of children undressing in changing rooms.
UK authorities were alerted in 2012 in a global operation but Essex Police did not speak to him until 9 September.
Jim Gamble, the ex-Child Exploitation and Online Protection Centre (CEOP) head, said the failings were "awful".
The Home Office has been asked to comment.
Mr Goldberg, who taught at Thorpe Hall School, was found dead the day after being interviewed by police.
His name was on a list of people who had bought online DVDs and videos, some of which showed graphic images of children.
Toronto Police's "Project Spade" passed the list to the UK's Child Exploitation and Online Protection Centre (CEOP) in July 2012.
The unit did not share the information with local police forces until November 2013 and then Essex Police failed to act on it for 10 months.
Names on the list included the Suffolk doctor Myles Bradbury, who this month admitted abusing young patients at Addenbrooke's Hospital in Cambridge.
The delay in passing the information on is being investigated by the Independent Police Complaints Commission (IPCC).
Mr Gamble, who resigned in a row over CEOP's future in 2010, said: "This was an accident waiting to happen.
"When I resigned, we were dealing with 600 or 700 reports a month, and we were struggling with that.
"But in the last few years, CEOP has been dealing with 1,800 a month. It's not possible to deal with those volumes without there being huge room for error."
CEOP was absorbed into the National Crime Agency last October - something Mr Gamble believes diverted resources away from the unit.
"What is happened is awful, and I'm not trying to excuse it," he said.
"But what I don't want to see is the very few staff doing far, far too much work being demonised, when actually this is an issue that should go right to the heart of leadership."
Essex's Police and Crime Commissioner, Nick Alston, said he was concerned about the length of time it took Essex Police to act on the information about Goldberg once it had been passed on.
"In my judgement, there's been a failing here that we need to understand and put right," he said.
Home Affairs Select Committee Chairman Keith Vaz said the delay in acting on the information was "totally unacceptable".
He said he had written to the National Crime Agency and the Canadian authorities to ask what steps were taken after they acquired the details.
"It is vital that urgent improvements are made to strengthen international co-operation and speed up action following receipt of information, especially where suspects have daily contact with children in their place of work," Mr Vaz said.
Essex Police said it was acting on 18 lines of inquiry from Project Spade.
So far two people have been charged with possessing indecent images of children - one a fireman, another a bus driver. A third arrested man has been released.
The force said four other suspects are retired and the others are in low-risk occupations. Twelve properties have been searched.
Failings to fully investigate a teacher who took indecent photographs of pupils were "an accident waiting to happen", an ex-child protection chief has said.