DETROIT -

Tanya Zuvers They simply vanished.

Three young brothers from Morenci have been missing for the past two years. Investigators have released images showing what the Skelton brothers would look like today. The images are difficult for their mother, Tanya Zuvers, to see.

"Little boy features are all grown up, and it's like ... then you mourn that two years that we've lost," she said.

It was two years ago Thanksgiving weekend when the boys were sent to their father's Morenci home to stay with him during the weekend. They have not been seen since.

Police have received more than 1,300 tips but, so far, they have not had any luck. Their mother believes the boys are alive and that her ex-husband, their father John Skelton, placed them with another family.

"Did he say to someone, you know, 'My wife and I are divorced and I want my children in safe keeping until I can get my divorce,' or did he say, 'Oh, you know, poor me I'm a single dad. My wife died and just can't afford to raise my children ... can you take them and raise them for me?'" Zuvers said.

John Skelton Investigators don't buy it. They believe John Skelton killed his sons and disposed of their bodies, likely near the small town of Morenci. John Skelton now sits in prison in Michigan's Upper Peninsula. He was convicted on child imprisonment charges and sentenced to 10-15 years behind bars. He has said repeatedly the children are with other people but he won't reveal where.

Read more: Missing boys' mother seeks answers from imprisoned ex-husband

Until the mystery is solved, Zuvers won't stop searching and believing.

"Someone somewhere knows the truth, besides John Skelton," she said.

Age-progressed pictures of missing Skelton brothers
Age-progressed photos of Andrew, Alexander and Tanner Skelton.