Casper man sentenced to 11-16 years in prison for possession of child porn

CASPER (WNE) — A Casper man who pleaded guilty to nine counts of sexual exploitation of children was sentenced to 11-16 years in prison on Tuesday morning.

Prosecutors asked for the maximum allowed penalty under a plea agreement for Matthew Nick Leslie, 49. 

Leslie was convicted of possessing more than 170,000 files of child porn with victims varying in age from infancy to pubescence, according to court documents.

Leslie’s plea deal was structured unusually, which was noted by district court Judge Kerri Mae Johnson in Tuesday’s sentencing hearing.

While the state didn’t agree to any specific sentencing recommendation cap on individual charges, prosecutors did agree to ask for no more than 16 years cumulatively. Each charge Leslie pleaded to carried a maximum penalty of 10 years’ prison time.

Ultimately, Johnson agreed to abide by the agreement.

“The amount of material you had is alarming,” Johnson told the defendant after handing down the sentence.

Authorities became aware of the illicit materials in Leslie’s possession after his wife became “suspicious of her husband’s ... pornography consumption” and began to check on his computer usage, according to an affidavit filed with the charges. Leslie’s wife told investigators that she found CDs with hundreds of files of child sexual abuse material stored on them.

According to authorities, Leslie’s desktop computer, iPhone, 50 DVDs, a Surface tablet and 19 USB drives, SD and microSD cards contained more than 27,000 images of “sex acts” and “lascivious exhibition” and an additional 143,000 images of what investigators described as “child erotica.”

A second affidavit includes file descriptions of several items found in Leslie’s possession. In the document, images are in several groups identified as “infant/toddler,” “sadomasochism,” “bestiality” and the broader category of “child pornography.”

This story was published on Nov. 6, 2025.