Hong Kong (CNN) -- A billionaire who jointly controls Asia's biggest property development company and a former No. 2 official of Hong Kong were found guilty of conspiracy to commit misconduct in the city's biggest corruption trial.

The tycoon, Thomas Kwok along with his younger brother, Raymond Kwok were accused of bribing Rafael Hui, the government official, in offenses spanning nearly a decade. The Kwok brothers, who rank 86th on the 2014 Forbes list of the world's richest people, are co-chairs of the developer giant Sun Hung Kai, which is responsible for many of Hong Kong's most iconic skyscrapers.

The main question during their trial was whether they had bought the allegiance of Hui, Hong Kong's former chief secretary.

After five days of deliberation, a Hong Kong High Court jury found the older Kwok guilty of bribing Hui between 2005 and 2007. His younger brother was cleared of all charges.

Thomas Kwok, co-chairman of Hong Kong developer Sun Hung Kai Properties was convicted of conspiracy for making payments to a former government official.

Hui is the highest-ranking former official to face trial in Hong Kong. The court looked into whether Hui received monetary and housing benefits worth at least $4.3 million from the Kwoks in return for government decisions favorable to the company. The charges related to accepting rent-free apartments, unsecured loans and a consultancy agreement with the property company.

The jury found him guilty on three counts of misconduct in a public office, conspiracy to commit misconduct in public office and conspiracy to offer an advantage to a public servant.

The jury also found Thomas Chan, who was responsible for land acquisition at the company and Francis Kwan, a former Hong Kong Stock Exchange official, guilty for making a series of payments to Hui.

The sentencing hearing for the four who were convicted will be held Monday. Raymond Kwok was released from custody after his arrest in 2012.

As he left the court, Kwok said he had mixed feelings that he was free, but his brother had been found guilty.

The case caused a media frenzy in the city, where real estate is a local obsession. Sun Hung Kai, which helped to build some of the tallest buildings in the city's celebrated skyline, contributed to the Kwok brothers' estimated $18.3 billion fortune.

Hong Kong, a special administrative region of China, is considered to be one of the world's least corrupt territories. According to Transparency International's 2013 Corruptions Perceptions Index, Hong Kong is the 15th least corrupt territory in the world -- with the United States, by comparison, ranked 19th.

CNN's Paul Armstrong contributed to this report.