TUCSON, Arizona — Frustrated volunteers have taken the search for Nancy Guthrie into their own hands — combing the garbage-filled desert ditches and homeless camps near her home for clues.

And on Sunday, they came up with a possible lead — a black backpack was discovered just two miles away.

The Post was at the scene Sunday morning when the torn-up black, Swiss Gear-brand bag was found in a storm drain that doubles as a homeless encampment.

Volunteers found a backpack in a drainage pipe in Tucson, Arizona, as they searched for Nancy Guthrie.
A volunteer discovered a backpack in a storm drain during the search for Nancy Guthrie.James Keivom for NY Post
The location was a short drive from the 84-year-old Nancy’s house in the Catalina Foothills neighborhood north of Tucson.

Volunteer Catherine Lopez found the backpack around 11 a.m. in the tunnel just off West Orange Grove Road, close to State Route 77.

She called the Pima County Sheriff’s Office, and a deputy arrived around 15 minutes later.

A picture from the scene shows Lopez holding the backpack with a large stick while on the phone with the sheriff’s office.

A volunteer uses a phone while holding a stick and a backpack found in a drainage pipe.
Catherine Lopez on the phone with the Pima County Sheriff’s Office after finding the bag Sunday morning.David DeTurris/NY Post
Another photograph shows an officer wearing gloves gingerly picking up the closed backpack.

Two homeless people were in the storm drain at the time of the discovery, but the arrival of the authorities reportedly spooked them, and they fled.

A Pima County Sheriff's deputy picks up a backpack near a patrol car, found during the search for Nancy Guthrie.
A Pima County deputy was seen picking up the backpack shortly afterward.David DeTurris/NY Post
It doesn’t appear to be the same backpack as the masked perp wore in surveillance footage from Nancy’s Nest camera earlier this month.

This week, investigators identified that backpack as a black Ozark Trail Hiker, sold exclusively at Walmart.

Yet another glove was also found nearby on Sunday, just off North First Avenue.

Savannah Guthrie with her mother, Nancy.
“Today” show co-host Savannah Guthrie’s mother, Nancy, was last seen by her family on Jan. 31.Instagram/savannahguthrie
It comes as Pima County Sheriff Chris Nanos faces accusations that his ego is derailing the hunt for Nancy, whose daughter, “Today” show co-host Savannah Guthrie, 54, flew out to Arizona at the start of the month to aid the search.

With no suspects or persons of interest identified, more than three weeks after Nancy was reported missing on Feb. 1, authorities are set to scale back the search in the coming days.