Family and friends are pleading for help in finding an Arizona State University freshman last seen exiting a bar in Tempe, Ariz., on Friday.
Jack Culolias was last seen at Cadillac Ranch bar in Tempe Marketplace, Tempe police said.
His friend, Alec Pinto, was with him that night. They were both pledging the fraternity Sigma Alpha Epsilon (SAE) and were there as part of a fraternity social -- a bit of fun before they would go through initiation the following week.
"It had nothing to do with hazing at all, it was purely for fun," Pinto said.
Culolias got drunk and was apparently seen urinating off a balcony, which caused bouncers to escort him out of the bar, Pinto said. He has not been seen since.
On Saturday, Pinto got worried after not hearing from Culolias, who he normally talked with or saw every day.
"I was worried that no one had seen him and that he hadn't contacted me," Pinto said.
Pinto called Culolias and went to his dorm to no avail. He later discovered that Culolias' phone had been found at the bar.
On Sunday, as his worry mounted to fear, Pinto decided to try and get a hold of Culolias' family in Orange County, Calif. He eventually reached Culolias' mother, Grace Culolias, and urged her to file a missing person's report.
She filed a report with the ASU Police, but later reached the conclusion that the force was short staffed. So she drove down to Arizona herself to try to discover where her son was and how to bring him home.
"I felt like I was the one in charge of the investigation," Grace Culolias said.
On Monday, while searching a nearby river basin, an area Tempe police described as "desolate," she found a single red Vans sneaker, one that she knew belonged to her son.
She alerted the Tempe Police Department, which had taken over the investigation.
Culolias said the ASU Police told her the department had searched the area on Sunday night with flashlights, but she was critical of the department's actions during the first crucial hours when her son was reported missing.
"They did not do a good job," she said. "It they would have, they would have found the shoe on the second day instead of the fourth. ... They should have immediately turned it [the investigation] over."
The Arizona State Police Department did not respond to several ABC News calls for comment.
The Tempe Police Department said it has launched a complete investigation, employing a helicopter, K-9 unit and specialty equipment to search underwater. Investigators have found no evidence of foul play.
Culolias noted Jack was worried about initiation week, or "hell week," as she calls it.
"There is no sign of foul play," she said. "I'm hoping he may have hid because he didn't want to go through hell week. It may have had something to do with the fraternity but, at this point, I don't see any physical evidence."
SAE has a strict no-hazing policy and even condemns excessive drunkenness, Pinto said. The fraternity has started a fund to pay for the Culolias' out-of-pocket expenses while they stay in Arizona to search for Jack. In less than two days, the fund raised $2,712.
On the phone, Grace Culolias spoke of her undying resolve to find her son.
"I am all cried out," she said. "I'm a wreck but I can't sit in a ball and cry; that's not going to bring my son home. I'm at the search site because I want to make sure they [the police] are out here. It's giving me the peace of mind."
Anyone with information on the case is encouraged to contact the Tempe Police Department at 480-350-8311.