As the search for Nancy Guthrie continues, neighbors say a suspicious white van was spotted on their street, just days before the 84-year-old went missing.

Brett McIntire, who lives across the street from Guthrie, said he had informed the police about the unmarked van when he was questioned about whether he had noticed anything unusual in the days leading up to her disappearance.

“It was somewhere on that street. It was a white van, full-sized, with no printing on the sides. It was parked on the street,” McIntire told the New York Post. “Normally, people that are coming to work on your home will have a company vehicle, or if they’re independent, something written on it.”

McIntire and his wife could not recall the exact day the van had been spotted, but told the outlet that Guthrie’s disappearance had led them to consider installing security cameras.

News of the McIntire’s observation comes as the search intensifies for Guthrie. Investigators said Thursday they have no proof Nancy Guthrie is still alive after she was reported missing in Arizona on Sunday. The family has asked for proof of life after ransom notes were sent out to media outlets. As the deadline passed without contact, Guthrie’s son issued a plea for his mother’s return in a new Instagram video.

“Whoever is out there holding our mother, we want to hear from you,” said Camron Guthrie. “We need you to reach out, we need a way to communicate with you so we can move forward. But first, we have to know you have our mom. We want to talk to you, and we are waiting for contact.”

Authorities are now offering a $50,000 reward for information on Guthrie’s disappearance.