Seth Greenberg reacts to NCAA referee John Higgins receiving death threats from Kentucky fans after the Wildcats' loss to UNC in the Elite Eight. (1:45)

NCAA referee John Higgins met with law enforcement for more than two hours Tuesday after Kentucky fans sent death threats, repeatedly called his company's office and home -- despite an unlisted number -- and posted a barrage of false messages about his business on the company's Facebook page, sources told ESPN.

Higgins worked Sunday's Elite Eight game between Kentucky and North Carolina, which the Tar Heels won 75-73 on Luke Maye's buzzer-beating jumper. The Wildcats were whistled for 19 fouls, including two each on Malik Monk, De'Aaron Fox and Bam Adebayo in the first half, a fact that Kentucky coach John Calipari didn't let go unnoticed.

"You know, it's amazing that we were in that game where they practically fouled out my team," Calipari said. "Amazing that we had a chance."

Kentucky fan websites and message boards identified Higgins as making incorrect calls against the Wildcats. Calipari's statements, message board chatter and their own fury prompted some Kentucky fans to write false and damaging messages on the Facebook site of Higgins' company, John Higgins Weatherguard Inc., as reported by several outlets Tuesday.

But the nastiness went well beyond those posts. Sources said the phones at Higgins' home and business, also known as Rooferees, have been "ringing off the hook" since the game, with angry Kentucky fans calling to complain and some even going so far as to make death threats.

That prompted a meeting with law enforcement.

"We appreciate the passion that fans bring to college basketball," NCAA vice president Dan Gavitt said in a statement issued Wednesday. "But the behavior of some fans toward John Higgins that has been reported publicly after last weekend's regional final is not appropriate.

"John is one of the most experienced and qualified college referees in the country, evidenced by his many years of officiating during March Madness, and for some fans to not only question his character but also criticize his private business is unfortunate. While we understand it's nearly impossible to officiate a game without fans getting upset about a call, it's also important that behavior during or after a game reflects the same standards of good sportsmanship that we encourage of our coaches and student-athletes."

On Wednesday, Kentucky released a statement promoting good sportsmanship by Wildcats fans.

"While we were all disappointed to see a memorable season end on Sunday and we appreciate the support our fans showed our student-athletes all year, we encourage our fans to demonstrate good sportsmanship to everyone and discourage any other kind of behavior," the statement said.

Calipari also tweeted on the subject:

I always brag that we have the classiest fans in the country. Let's make sure we remain that way even after a tough loss. — John Calipari (@UKCoachCalipari) March 29, 2017

Higgins declined to comment when reached by phone, but sources said the official will work the Final Four in Glendale, Arizona.