Story highlights Local media report that Santos left the field this year to focus on his business

Police: The former football player's wife found his severed head on their doorstep

João Rodrigo Silva Santos played for mostly second-tier club teams before retiring

O Globo: Police investigate whether Facebook posts are connected to the crime

João Rodrigo Silva Santos didn't come home Monday night.

When the former professional footballer's wife opened the door on her way to work the next morning, she found his severed head on their front step.

The head was inside a backpack, police said. Santos' eyes and tongue had been gouged out, according to Brazilian media reports.

Now police in Rio de Janeiro are investigating the grisly killing, though they haven't said who they believe is behind it.

Santos, 35, was a forward for a number of mostly second-tier Rio de Janeiro football teams before retiring and opening a health foods store.

His death comes at a time when football fans worldwide are shifting their focus toward Brazil, which will host the World Cup in 2014.

Late last year, the country announced it was pumping $900 million dollars into its security budget to make the competition "one of the most protected sports events in history."

World football's ruling body FIFA had expressed concern about Brazil's increasing crime rate, particularly in Sao Paulo.

One police official told Brazil's O Globo newspaper that authorities are investigating whether a recent post on the store's Facebook page could be connected to the crime. The post showed surveillance footage and asked for help catching shoplifters.

Police plan to compare the images to surveillance footage taken at the shop Monday night, chief homicide investigator Rafael Rangel told the newspaper.

CNN affiliate TV Record reported. The former football player was last seen Monday night, when two suspects entered his vehicle,

On Wednesday morning, police said they found parts of a man's body in a river outside the city and were testing the DNA to see whether the remains belong to Santos, TV Record said.

Authorities have interviewed 10 witnesses so far in the case, police said.

According to local media, Santos' wife, Geisa Silva, worked for the police in one of Rio's shantytowns, but as a social worker giving swimming lessons to children, not as a policewoman.

She told investigators she did not know of any threats made against her husband, according to TV Record.

Some of Santos' relatives and neighbors told O Globo that he didn't have any enemies and said they didn't know what could have motivated the attack.

Santos started his football career when he was 16 years old, and played for several Brazilian club teams. He played for the Bangu club team from 1996 to 2005, according to a biography on the club's unofficial website

In 1998, he played for Honduras' Olimpia club. And in 2003 he played for Sweden's Oster club, the website says.

The website calls Santos a "humble hero," describing how goals he scored brought victory to another club team he joined.