Mrázek, 47, a cooking-oil baron, was one of the country's richest and most powerful figures. Police now call the shooting a probable assassination, but have released few details.

"We have just taken over the case today," said Police Presidium spokeswoman Blanka Kosinová. "The chief of the division told us not to give out any information."

Mrázek was widely known as the head of Czech Oil, though his name doesn't appear as a shareholder. Czech Oil owns food company Setuza, which Mrázek ran, mostly behind the scenes, while his partner Tomáš Pitr represented it publicly.

Mrázek was shot in the chest around 8 p.m. outside Setuza's Prague 4 offices. Two associates were unharmed.

Investigators told media that a sniper used a rifle and specialized scope. The shot came from a distance, either an open garden or a nearby balcony, they said.

In the absence of specifics, the media has speculated on motives.

Police have not confirmed two of the most mentioned ones: that it involved Setuza's business dealings — which featured prominently in a 2005 scandal surrounding the privatization of chemical company Unipetrol — or that it was over Mrázek's involvement in shady schemes in the 1990s.

Amassing a fortune

A criminologist on the investigation told Právo that fugitive billionaire Radovan Krejčíř, now hiding in the Seychelles Islands, is among the suspects. The criminologist cited a 2002 letter in which Krejčíř called Mrázek as a pig and said, "for every pig, there is a butcher."

Reports have estimated that Mrázek controlled interests here worth tens of billions of crowns.

Mrázek began building his fortune in the 1970s, when he began selling electronic devices to the Russians. His involvement with the communist regime reportedly deepened in the 1980s when he became a regular collaborator for the secret police.

After the 1989 revolution, Mrázek invested his fortune in a number of Czech businesses, including the Eggenberg brewery, the Seliko canning factory and the food company Agrocredit, which owned shares in Setuza.

Mrázek soon took over Agrocredit, and with a few business partners, including Pitr, took control of Setuza in 2000 following suspicious circumstances involving the sudden closing of Investiční a poštovní banka.

Setuza, which is 4.1 billion Kč ($177.7 million) in debt, objected to the government's sale of Unipetrol to Polish company PKN Orlen. Setuza had been interested in several companies that were part of PKN Orlen's total holdings, but the company chose Setuza's rival, Agrofert, as a partner instead.

A business partner of Mrázek first raised allegations of corruption in the privatization to the Polish Parliament, a move largely seen as an effort to undermine Agrofert. Polish lawmakers promised an extensive investigation into the deal. Should the allegations prove true, the sale would be canceled and returned to general bidding.

Authorities have long tried to connect Mrázek to a number of bank frauds and tax schemes, as well as murder conspiracy charges, but have never been able to prove his involvement.

Mrázek survived one assassination attempt in 2002, when a lone gunman opened fire on his car as he returned home from work.

From that time, Mrázek traveled in a bulletproof Toyota Land Cruiser.