New details have emerged in the search for missing 19-year-old Middlebury College freshman Nicholas Garza that could link him to the so-called "Smiley Face Gang," which a group of retired detectives believes is responsible for the apparent drowning deaths of dozens of young men across the country.

Searchers have found smiley-face graffiti near Garza's campus like that painted near some of the locations where about 40 bodies have been discovered across 11 states, FOX 44 News reported. Garza’s mother thinks that discovery could link her son's disappearance to the deaths of the other mostly college-age victims.

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Volunteer searchers have come forward with pictures of the smiley face, found on a utility shed door a short distance from downtown Middlebury, Vt. The photos were taken a week-and-a-half ago, when the group was scouring a river bank for clues.

When the volunteers saw New York detectives describing the alleged gang of serial killers on national TV and saw pictures of the graffiti discovered in some of the other cases, they realized the striking similarity to the drawings they had photographed, FOX 44 reported.

The graffiti on the shed was almost identical to that painted near some of the spots where the young men's bodies have been found, typically in rivers.

"When you're walking around, you notice there's graffiti but you're not paying attention to what's out there," Nicholas' mother, Natalie Garza, told FOX 44.

Garza was last seen walking out of a dormitory Feb. 5. When friends couldn't find him the next day, they notified campus security, but his mother didn't file a missing persons report until five days later because friends thought Garza might have left campus to go to a cabin that was out of cell-phone range.

Middlebury police believe the graffiti is more than two years old and are not following up on leads related to the alleged gang.

Officers have been searching the water for Garza after an airplane captured a picture of what appeared to be a body several weeks ago.

"Nick didn't walk off this campus and he was in his right frame of mind, and I believe somebody knows what happened to my son that night," Natalie Garza told FOX 44.

Searches of the 350-acre campus have yielded no clues as to what happened to the student. The last large-scale hunt ended Feb. 23, though there have been spot searches since then. All 109 buildings on campus have been combed through twice, as have their rooftops.

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The Associated Press contributed to this report.