Threats allegedly sent to former Luton manager Nathan Jones are being investigated by police.
Jones, 45, left the Sky Bet League One Hatters last month to take over at Championship club Stoke.
Luton were second in the table when Jones left and the Welshman's departure was unpopular with some supporters.
Hertfordshire Police said the force was investigating following reports that a man in his forties has received malicious communications.
Jones guided Luton to promotion last season having been appointed in January 2016 and admitted it was a "real wrench" to leave Kenilworth Road.
"The amount of times I've cried from text messages from players... it makes me emotional because I was married to the club," Jones said. "It's a calculated gamble but it's the right step for me and the club. I think I've left them in a wonderful position.
"It really wasn't (an easy decision). I had a really good place at Luton, it was a wonderful club. We were in a wonderful place.
"When it happens you just have to put things aside and think professionally. It was a real wrench, we built something special at Luton and it would have taken something special. I had the opportunity to leave (before) and I never did, when this came up it was too good to turn down."
Luton are currently top of League One under caretaker manager Mick Harford while Stoke are 15th in the Championship after four defeats in their last five league games.
