For the Mamic brothers, Zdravko and Zoran, the Dinamo Zagreb chief executive and manager respectively, the team’s Champions League campaign began in a jail cell.

The pair were bailed from Zagreb’s Remetinec prison only on the afternoon of Wednesday 15 July and they hurried to the Maksimir Stadion in time to see Dinamo take on Fola Esch from Luxembourg in the first-leg of the second qualifying round.

The brothers had spent 11 nights in the jail after their arrest on charges of embezzlement, tax evasion and bribery, which relate to their alleged siphoning of funds from big-money transfers to overseas clubs – the biggest of which was Luka Modric’s £16.6m move to Tottenham Hotspur in 2008.

The Mamics and Damir Vrbanovic, the Croatian football federation executive president who was previously one of Dinamo’s key employees, are alleged to have taken at least £11.1m, together with a further £1.1m in unpaid taxes, which it is claimed they got with the help of a corrupt taxman. Vrbanovic, who has reportedly denied the charges, and the tax inspector, who has not said anything, were also arrested and jailed.

Modric and others have been dragged into the scandal, according to reports in Croatia, with the midfielder, now of Real Madrid, having been called to give his testimony.

It is the incredible story that has Croatia in thrall, has cast a dark shadow over Dinamo – firing anger, loathing and boycotts among a section of their supporters – and provides the backdrop to their opening Champions League Group F tie against Arsenal at the Maksimir on Wednesday.

“It’s difficult to say which has been my favourite group stage qualification,” Zdravko Mamic told Vecernji List, one of Croatia’s major daily newspapers, on 27 August, after Dinamo’s play-off win over Skenderbeu Korce of Albania. “But maybe it is this one because it’s our latest and it was won in circumstances that were the hardest. They were almost impossible for us.

“We survived many imputations and attempts to destabilise the club. I don’t remember anyone, in any walk of life, achieving a similar success in such a bad environment.”

The Mamic brothers were arrested on 4 July, when they crossed into Croatia from Slovenia, where Dinamo had held their pre-season training camp. Police had searched offices at the club and the Croatia football federation, along with the brothers’ homes.

The authorities wanted to remand them in custody for a month and the brothers’ initial plea for bail was rejected. But they appealed and won. Zdravko had to pay £700,000 and Zoran £380,000 while Vrbanovic paid £83,000. The investigation is ongoing – no date has been set for their trial – and the brothers have, more or less, carried on as normal.

They made it to the Maksimir in time for the kick-off against Fola Esch, although Zoran sat in the directors’ box rather than on the bench, having designated control of the team to his assistants, Damir Krznar and Igor Cvitanovic. He did reportedly give the pre-match and half-time team-talks.

When the Mamic brothers arrived at the stadium it was the prompt for thousands of Dinamo’s Bad Blue Boys to leave. The supporters’ group have been locked in a long-running feud with the brothers as they feel that Zdravko in particular has taken the club from them and turned it into his family business.

Zdravko does not own Dinamo, which is set up as a citizens’ association, but he has total control. The Bad Blues Boys, who have been in exile, have disputed the way that he runs things and want the right to vote in leadership elections, but he has outmanoeuvred them.

The Mamics were in jail when Dinamo kicked off the league season at home to Hajduk Split on 12 July, and so the Bad Blue Boys made their return; the Maksimir rocked to a passionate beat during the 1-1 draw. The crowds have generally been low, although Arsenal’s visit ought to buck the trend. There was disgust among the Bad Blue Boys, however, when the Mamics turned up against Fola Esch – they had not known that they would be released.

At the stadium Zdravko, in characteristically outgoing fashion, said: “If Daddy had been at the stadium against Hajduk we would have beaten them by five goals.” Zdravko is known, in some quarters, as Daddy because, well, he is The Daddy.

Those who champion him see a shrewd entrepreneur; an iron-fisted negotiator with remarkable connections to the police, judiciary, media and politics, who has built Dinamo into perennial league champions. They have won the title in each of the past 10 seasons and are currently top of the table, with five wins and four draws from their opening nine fixtures. Zdravko is generally considered to be the most powerful man in Croatian football.

His enemies, though, speak of an aggressive and vulgar bully who is obsessed by personal financial gain. His exacting standards and hair-trigger temper have seen him sack a host of managers during his tenure, which began in 2003, before he turned to Zoran in August 2013, initially on an interim basis and, from October of that year, as the permanent manager.

Zoran, who had no previous coaching experience, enjoyed two spells as a player at Dinamo – at the beginning and end of a decent career which saw him capped by Croatia; he was in the World Cup squad that finished third at France 98, although he did not play a minute of the tournament.

He played for Dinamo against Arsenal in the 2006 Champions League play-off, however, which Arsenal won – the only previous meeting between the teams. After his retirement in 2007 he was appointed as Dinamo’s sporting director and he has been at the club ever since. He has combined the job of first-team manager with his director’s role.

The brothers are hell-bent on proving their innocence, with Zdravko having dismissed the charges as “absolutely pointless and constructed”, as well as claiming they were politically motivated.

The prosecution, though, will attempt to prove that they devised schemes to draw money out of the club through the sale of players such as Modric and Dejan Lovren, who moved to Lyon in 2009 and is now at Liverpool.

The Arsenal game seems like a high-profile distraction. The trial, whenever it happens, promises to be explosive.