The elder DeOrr Kunz says the boy's mother has "aged 10 years" since her son went missing on July 10

Credit: Courtesy Help Find Deorr Kunz/Facebook

It has been seven days since Jessica Mitchell has seen her 2-year-old son DeOrr Kunz – and it’s taking a visible toll on her.

“The look on her face – in seven days it looks like she’s aged 10 years,” Mitchell’s father-in-law, also named DeOrr Kunz, tells PEOPLE. “Her baby is gone.”

On July 10, while on a family camping trip in the mountains near Leadore, Idaho, little DeOrr disappeared, officials say. The Lemhi County Sheriff’s Department received a 911 call at about 2:30 p.m. after the boy had been missing for an hour. “We’ve had people out there since this first started,” says a spokesman for the department. “Every avenue is being investigated.”

The elder Kunz says the boy’s parents were setting up camp and assumed Mitchell’s grandfather, who was also on the trip, was watching the boy. The grandfather assumed the boy’s parents were watching him, says Kunz.

“There’s a four-minute window where no one had an eye on him,” says Kunz, 70. “My grandson is paying the ultimate price for this.”

As of now, investigators are still combing the camp site, officials say. The boy’s parents refuse to come down from the site until they have a definitive answer that their son, who loved trucks and carried a baby blanket, is not there.

“My family has been torn apart,” says Kunz. “He’s my little buddy. I don’t wish this on anybody.”

While Mitchell, 25, continues to wait for any news, she clutches her son’s baby blue blanket, which he left behind.

“The blanket was in the truck, so Jessica now has got that blanket and she will not let go of it. She holds it, smells it, loves it,” Kunz says. “It’s the only attachment she has to that boy right now.”