This stems back from games in 2003/2004 season, when Porto won the league under Mourinho. The investigation started out fairly low level where Uniao de Leiria were found, via phone leaks I believe, to have attempted to bribe referees for matches, offering golden whistles, cash and even prostitutes in an attempt to influence decisions. There are a shit-load of people who were under investigation, and these rumours have been around for ages with FC Porto.
Except during the investigation of Uniao de Leiria, Pinto da Costa's ex wrote a book where she made a load of allegations claiming Pinto da Costa was involved in bribing match officials.
during the last few years conversations have been unearthed which implicate particularly Valentim Loureiro from Boavista and the loveable Pinto da Costa.
With Porto the matches in question were against Estrela de Amadora and Beira Mar.
We say here how refs favour Man Utd, but I have seen some absolute diabolical decisions over the years for Porto, going back to early 90s.
This is an old article about Porto even before the Golden Whistle investigation began:
"Over the years, suspicious refereeing has been associated with various referees in Portugal favoring FC Porto. Nothing has been proven, but there have been some strong indications that the allegations are true.
FC Porto’s title in 92-93 was marred by some dubious results. One that stands out was a 1-0 away victory at Famalicao in which the referee at the time allowed over six minutes of injury time in a game with no injuries and no prolonged stoppages. Of course, FC Porto scored in the sixth minute of injury time. This game followed several away victories in which FC Porto received the benefit of the doubt on several calls in previous away matches.
The scandals of 1996 then put the referee situation in full view. First, FC Porto was caught paying vacation trips to Brazil taken by former referee Carlos Calheiros. FC Porto’s travel agency used the referee’s two middle names to identify his account. How is a referee to remain partial when one team is paying for his and his family’s vacations abroad? The consequence was Mr. Calheiro’s nomination for president of the referee’s union being denied, and no punishment was given to FC Porto.
Later it was discovered that a member of the Porto’s front office approached the referee of the semi-final Cupwinner’s Cup between Porto and Aberdeen in 1984 and attempted to bribe him to facilitate Porto’s scoring chances. Porto went on to win 3-0 without any controversial calls. It turns out they didn’t need the help. They ended up losing the finals to Juventus 2-1.
The referee association and unions have become centers for controversy and suspicion in the election of its leaders and presidents. It seems that the stronger districts such as Porto’s are able to influence votes for their candidates. In turn those elected appoint the referees for the matches. A proposed lottery system in the selection of the referees was quickly dismissed. Therefore the end result is the ability to have certain referees cover certain matches. "
Pinto da Costa is known to be a corrupt bastard. Regarding the 2 matches in 2004, the accusation is that Pinto da Costa handed Augusto Duarte and envelope with 2500 Euros to smooth over the results of those games
The case is known as "Apito Dourado" which means Golden Whistle, like some of the gifts which were allegedly being given to referees.
Here were the punishments given out:
Referee Augusto Duarte has been banned for 6 years for bribery in matches involving Porto and Boavista in 2003/2004
President of Leiria has been suspended for 1 year and fined 40000 Euros for attempting to fix a match against Belenenses in 2003/2004
Pinto da Costa suspended for 2 years and fined 10000 Euros (LOL) due to match fixing charges against Amadora, Beira Mar, Benfica and Académica in 2003/2004
Porto docked 6 points from season just ended and fined 150000 Euros
Boavista relegated to Liga Vitalis
Former Boavista chairman Valentim Loureiro is suspended for 2 years due to match fixing charges between Boavista and Belenenses, Benfica and Académica in 2003/2004
Edit: Joao Loureiro, Valentim's son was the one punished. Valentim Loureiro seems to have mysteriously escaped punishment despite his name being one of the most prominent of those mentioned when charges first came out.
As an aside, Boavista is also a Porto-based club