Bulgaria's football is deeply involved in mafia businesses - match-fixing and money laundering are just the tip of a criminal iceberg that lurks beneath the surface of the beautiful game, a BBC investigation has shown.

"Bulgaria holds a grim record – it is the country with the most murdered football club owners in the world. No fewer than 15 football club bosses have been murdered in Bulgaria's top football league in the last decade alone. A symptom of what is said to be the endemic link between football and organized crime," Margot Dunne comments in the latest edition of Crossing Continents.

The BBC investigation was triggered by continuing reports that the game is riddled with corrupt practices including match-fixing and the illegal procurement of European Union passports for overseas players.

Crossing Continents examines these claims, attending a match which has allegedly been fixed in advance.

The game is a tense fixture between majors Levski and Lokomotiv Plovdiv, but BBC sources say its outcome has been prearranged and the lead will switch dramatically after half-time.

Levski takes a 2:0 lead in the first half of the game, but in the second half Lokomotiv Plovdiv are suddenly back in the match with two successive goals. Then five minutes before the end of the match, another twist, a penalty goal, comes to seal Lokomotiv's victory.

The crowd is booing the referee as he is walking off the pitch. The journalist talks to Levski fans, who claim everybody knows the referee was paid.

The deep suspicions are having a corrosive effect on the football support in Bulgaria and fans already prefer watching foreign football clubs, Margot Dunne comments.

The program meets Todor Batkov, chairman of one of the country's best known football clubs, Levski Sofia, who accepts that corruption in the national game is as deep rooted as ever, but claims his club plays for victory in every game.

The program recounts the experience of a sports journalist from TV Channel 3, who received in November 2011 a match-fixing alert by Yordan Dinov, representative of an international online gambling company.

In a telephone conversation, Dinov said that massive amount of betting suggested that the match between Lokomotiv Plovdiv and Litex was fixed. The lead was about to switch, he claimed, in favor of Plovdiv in the second half and this is exactly what happened.

Dinov voiced publicly the allegations at a press conference later. Despite detailed evidence, there was no police investigation, no officials or players were charged. For Dinov the story did not end there – he was shot dead in April this year while walking downtown Sofia.

"It is a public secret that chairmen, presidents of football clubs, football players, referees, are part of the football betting mafia," sports reporter Lazarov told BBC.

Unlike many journalists, who struggle trying to make football players talk openly about the problem, BBC got lucky.

Just as he was leaving on a one-year loan deal to Germany, Stefano Kunchev, an up and coming star, Bulgaria's leading under-21 goal-keeper, agreed to talk to BBC at the airport.

Kunchev says he decided to go public with an incident that occurred six months ago. Returning from training late last year, he was attacked and beaten by two men, who said nothing.

Kunchev put two and two together on the next day, when a man approached him, offering him 20,000 euros to throw an upcoming international match.

"Beating was the stick it seems, this was the carrot," Dunn comments.

Kunchev says he refused to take the money because he can not sell his country for 20.000 euros and has decided to go public with the story because of his family and the future of Bulgaria's football.