A compact disc was left in an envelope for police officers with a troubling note.

"I work in a computer repair shop," the anonymous note said, left with the London police two years ago.

"Enclosed is a sample of the findings off the desktop client's system. It appears he is a teacher."

Hours later on June 22, 2009, John Maycock, 55, was summoned to the principal's office at St. David's elementary school in Dorchester, not to discuss a pupil, but to be arrested.

On Monday, Maycock, 55, who taught Grade 4, was sentenced to nine months in jail, to be followed by two years of probation, for possessing a cache of child pornography of prepubescent girls. His collection consisted of 4,009 images and 180 videos totalling more than 28 hours in length.

Since his arrest, Maycock has lost his job and will have his teaching licence revoked.

He pleaded guilty to the charge earlier this year following unsuccessful Charter of Rights arguments.

During those arguments, Superior Court Justice Wolfram Tausendfreud was told police found a folder called "dinner music" on the disc left for them to look at.

In it was a large number of video and pictures of nude prepubescent girls.

Also on the disc were two files containing report cards prepared by Maycock.

Maycock told officers who came to the school he did send his computer out for repairs and agreed there was child pornography on the hard drive.

The computer was seized from Maycock's home.

Along with the child porn, police found 1,975 child nudity images, along with other photos of children and adult porn.

Assistant Crown attorney Karen Bellehumeur asked for a 12-month term, noting Maycock's pre-sentence report said he didn't show he had much insight into his crime.

Maycock said he collected the images when he had "too much time on his hands" when he was on a medical leave, the report said.

Bellehumeur said Maycock downloaded the images over and over again and kept scenes of child abuse on his computer.

She stressed that none of the children Maycock came in contact with as a teacher were compromised or in any photos found.

Defence lawyer Alejandro Munoz reviewed Maycock's extensive teaching background that began in 1980 and took him to Nigeria, Manitoba, the Northwest Territories, Huron County and finally to Dorchester, where he was employed by the London District Catholic school board.

He doesn't have a criminal record, is remorseful and has the support of his wife and family, Munoz said. Munoz suggested nine months.

Tausendfreund called it "a mid-level range" collection, but added that "4,000-plus innocent parties" - the children in the images - had been victimized.

He addressed the "insidious aspect of child pornography" and said there wouldn't be a market for the images if there weren't people who bought them.

"It involves innocent children who are unable . . . to properly speak for themselves."

Maycock's teaching career, Tausendfreund said, is "a matter of the past for him."

Tausendfruend recommended Maycock serve his sentence at the Ontario Correctional Institute in Brampton where he can receive sex-offender counselling.

He also ordered that Maycock's name be added to the federal sex offender registry for 10 years. Maycock also must stay away from schools, playgrounds and daycare centres and not to be employed in any job involving children.