A Perth man caught with more than 20,000 images and videos of child pornography will spend at least the next two years behind bars, after also indecently dealing with two boys.
Matthew William Evans, 33, pleaded guilty to three counts of indecently dealing with a child over 13 and under 16, two counts of possession of child exploitation material and one count of indecently recording a child over 13 and under 16.
The charges related to offences committed on two boys at Evans' Canning Vale home in 2015.
One boy woke up one night to find Evan's hand near his genitals.
On another occasion the boy woke to find the boxer shorts he'd worn to bed had been removed.
Photographs taken by Evans were later found of the boy with the boxer shorts either partially or fully removed, and his genitals visible.
Several photos showed the offender's hand touching the boy's genitals.
After this incident, Evans took the boys on a camping trip, where he indecently dealt with the other boy by touching his genitals while he was sleeping.
The boys filed a formal complaint with police on October 2, 2015.
A subsequent investigation uncovered 781 photos of the boys taken by Evans, with a number of the images captioned with sexual comments.
Police arrested Evans in November, 2015 and seized computers and thumb drives from his home.
They found 18,862 images of hard-core child pornography, and 3,533 videos of child exploitation.
During an interview with investigating officers Evans admitted to having an interest in gay porn, but claimed not to know it was illegal to possess child pornography.
A psychological report prepared for the court said Evans, who spent up to three hours a day watching pornography prior to his arrest, sought to "justify, minimise and externalise blame" for his offending.
District Court Judge Bruce Goetze said it was likely Evans' offending was motivated by "deviant sexual interest".
"You were in a position of trust with respect to [the boys]." he said.
"They were vulnerable in your own home.
"And then when you have child pornography that adds to the offending."
Evans was sentenced to four years' imprisonment, but was made eligible for parole after two years.
