Ahmed Dogan, the leader of the Movement for Rights and Freedoms party in Bulgaria, escapes an apparent assassination attempt Reuters

It was a shot almost heard around the world as millions watched a man storm a stage in Bulgaria and then point his gun at a prominent opposition politician live on television.

But many in Bulgaria are now trying to separate fact from fiction as they try to be clear about what motivated the attack.

Police took Oktai Enimehmedov, 25, into custody after he pulled the gun on Ahmed Dogan, the leader of the Movement for Rights and Freedoms (MRF), a party supported by Muslim voters including some Turks in Bulgaria.

Police now say Enimehmedov was holding a gas pistol that was loaded with pepper spray, with two other "bullets" being simply noisemakers. He pointed the gun at Dogan's head during a party congress in the capital, Sofia, but failed to shoot. He was tackled to the ground and beaten by guards and party members as TV cameras continued to roll.

Enimehmedov, an ethnic Turk, reportedly left a note at his home addressed to his mother, saying he had no intention of killing the party leader but simply wanted to show him he was not "untouchable".

Nedelcho Stoychev, head of the interior ministry's psychological unit, said the note showed Enimehmedov believed he would not survive the attack.

Police said they thought Enimehmedov, an architecture student with a criminal record for drugs, theft and assault, had acted alone. But officials have been forced to address claims the party may have staged the "assassination attempt" itself in order to boost its image.

Boyko Borisov, the prime minister, said on Sunday that he believed the attack was "probably not staged". He said: "This is a worrying event that should not take place in modern Bulgaria."

The MRF has been dogged by accusations of political and economic corruption for years. Dogan, who has led the party for nearly 25 years, was acquitted of corruption charges at a high-profile trial two years ago.

"It seems like [the gun pointing was] a pretty artificial attempt to present their party as a victim, to rally their voters, to strengthen their line," said Ivan Dikov, editor of Sofia News Agency, Bulgaria's main English-language news resource. "They have a lot to recover from."

Hours after the attack Dogan appeared at the party congress to a standing ovation to go ahead with a planned resignation. His longtime aide, Lyutvi Mestan, is expected to replace him. Observers in Bulgaria believe Dogan will find a way to continue his political career while maintaining control over the party.

"Now he's this targeted leader, the spiritual head of his community – like a victim, a martyr," Dikov suggested.

Bulgaria is due to hold parliamentary elections in the summer. The MRF was a junior partner in the previous Socialist-led cabinet before switching to the opposition, following elections in 2009.

Yet discontent with the MRF has been growing, including among its supporters. "Even among ethnic Turks in Bulgaria he's considered pretty controversial," Dikov said. "He runs the organisation really tightly, there's a system of patronage and nepotism. It's plausible that there was somebody who hates this sort of 'tyrant' who just wanted to get rid of him, and was ready to sacrifice himself."

The gun used by Enimehmedov, who could face six years' jail, could not have delivered a fatal shot, police said.

Beyond the attack and brawl, Bulgarians are watching this case closely because Enimehmedov's brother, Metin, shot to fame in 2007 after winning the Bulgarian reality show Dance with Me. "He was a terrific dancer," Dikov said.