10News learned investigators found a carton of eggs and prescription sunglasses belonging to Summer McStay on the kitchen counter.

"The whole thing just doesn't add up. It doesn't make any sense," said Mike McStay.

McStay said his brother, Joseph, sister-in-law Summer and two nephews would not just disappear. The family has not been seen since Feb. 4.

Inside the McStay family's home, Mike McStay and other family members watched a surveillance video obtained by sheriff's detectives that showed two adults walking with two children across the U.S.-Mexico border.

"This is not definitive enough for me to get a positive ID. It just doesn't give me enough," said Mike McStay.

Even McStay's mother said she could not identify her son from the pictures, but investigators told 10News the timing of the video is correct and the fact that the children appear to be wearing beanies might also be a clue.

Mike McStay remains skeptical, however, and after more than a month without hearing from his brother he said he can't believe he's gone.

"It's surreal …I call his phone to hear his voice … it just doesn't make sense," said Mike McStay. "The reality is we all need to be on the same page. My family's missing. They're good people. Let's go get 'em, and let's find 'em and bring 'em home."