A British executive accused of heading a $100m ticket-touting ring has completed two weeks in a notorious Brazilian prison, despite growing evidence that his detention may be procedurally and substantively flawed.

Ray Whelan, who as chief executive of the Match group managed a lucrative Fifa contract for the marketing of VIP tickets and hospitality packages, has been accused of running a parallel international touting operation, and was arrested during the World Cup finals in Brazil.

The allegations were based on telephone conversations intercepted by Brazilian police investigating an Algerian ticket broker, Lamine Fofana, one of 12 people accused of criminal activity relating to ticket touting.

Match has denied that there was any illegality in the transactions, stating that Whelan was acting within the framework of the Fifa contract and, in this case, selling returned tickets at their face value.

Whelan’s lawyers are particularly worried about the denial of bail and possible flaws in an investigative process that, they say, was timed to reach its climax as close as possible to the World Cup final.

Whelan, 64, was first arrested on 7 July, based on evidence contained in the intercepted telephone conversations, but he was released on bail just 10 hours later.

A judge accepted Whelan’s offer to submit his passport and imposed conditions that prevented the executive from leaving the city for more than eight consecutive days without communicating his absence.

On the eve of the World Cup final, however, audio recordings of Whelan’s phone conversations were leaked to the Brazilian media and – almost simultaneously – a state public prosecutor sought a new warrant for his arrest and detainment, which was granted by a different judge .

Whelan became aware of the gathering of reporters outside his Copacabana hotel and, advised by lawyers, left by an employees’ side exit.

CCTV images of Whelan leaving the hotel in this way were relayed on national television and police investigators at one point accused his lawyers of aiding the escape of a fugitive. Whelan presented himself to a judge two days later and has been detained in Rio de Janeiro’s Bangu prison since then.

The first bail order purported to rule against further detention, unless new factors – such as a breach of conditions – emerged. “There are several irregularities, but a fundamental point is that a previous release order of habeus corpus was still in place, and my client was respecting its conditions, so it should have taken precedence over the second detainment order. He was never a fugitive,” said Fernando Fernandes, the lawyer representing Whelan.

Prosecutors declined to explain why they sought the re-arrest of a defendant who was apparently complying with bail conditions. “There are legal criteria for ordering preventative detention, such as preserving the public order or guaranteeing the continuity of an investigation. I was satisfied that the requirements for preventative detainment were met,” said Marcos Kac, the state prosecutor on the case.

Whelan has now been charged with a longer list of offences, including illegal touting, corruption, money laundering, tax evasion and criminal association. In doing so, the Brazilian police seem to have made connections with other ongoing investigations into ticket-touting schemes, defence lawyers say. The crux of the prosecution case is that Whelan knew that Fofana was connected to an organisation that would re-sell the tickets for profit, Kac said.

Police said they recorded 900 calls between Whelan and Fofana during the World Cup, and that virtually all of them referred to the selling of tickets. “Forfana is a personal friend of Ray. They spoke about the sale of some unwanted tickets that were returned to Match by a hotel group. Ray can clearly be heard referring Fofana to the Match website to pay for the tickets, in accordance with the correct procedure. The prices may seem high to ordinary spectators, but they are as published in Match’s own brochure,” Fernandes said.

Defence lawyers have so far only had access to the recordings of telephone conversations that were illegally leaked to the media. Attempts to seek disclosure of the other recordings have so far been foiled by failings in the digital access system, Fernandes said.

As such, Whelan has not yet had an opportunity to deny the claims that a significant portion of the calls was carried out in French, a language that he apparently does not speak. “I think the Brazilian police wanted to make high-profile arrest on the weekend of the World Cup final. By leaving the Copacabana Palace hotel, Ray denied them the TV images they wanted of an international suspect being handcuffed. Perhaps he is paying the price for this,” Fernandes said.

Whelan has the official backing of Fifa in his fight for freedom. In an official declaration sent to Brazilian authorities, the Fifa general-secretary Jérôme Valcke states that: “Fifa trusts in the loyal and respectable business behaviour of Match Hospitality, Byrom plc, its staff and principles, including Mr Ray Whelan, and is confident that an assessment of the facts and underlying business concepts in relation to the sale of hospitality packages, will exonerate Mr Ray Whelan.”

Match won the Fifa contract after bidding in a competitive tender in 2007. Fifa sold hospitality rights for the 2010 and 2014 World Cups for $240m and has a $300m deal in place with Match Hospitality and Match Services for the next two tournaments as well.

With a nephew of Fifa president Sepp Blatter among Match’s minority shareholders, however, the ticket-touting allegations have done little to improve the governing body’s image.