US air marshals shot and killed Rigoberto Alpizar on 7 December as he boarded an American Airlines plane for Orlando, saying he had claimed to be carrying a bomb in his backpack.
Law-enforcement officials later said there was no sign of a bomb, and relatives of the Costa Rica-born naturalised US citizen have demanded an explanation from the US government.
About 600 people packed a small green and white church in Alpizar's home town of Cariari on Tuesday, a village surrounded by banana plantations 113km east of the capital San Jose, to bury him amid tropical heat that gave way to a downpour.
Alpizar's wife Anne, a US citizen, father Carlos and other members of his family sat in the front pews weeping during the Roman Catholic church service.
Anne Alpizar told Miami-Dade police department her husband had been diagnosed with bipolar disorder, a mental condition also known as manic depression, but the 44-year-old slain man's siblings have denied he suffered any such illness.
"The way they describe him makes you think he was a terrorist," said Carlos Alpizar, 36, brother of Rigoberto. "We want a transparent investigation that clarifies the incident and clears my brother's name."
Alpizar criticised the US marshals for using deadly force, saying they could have proceeded differently between warning his brother and pulling the trigger. He wondered why they did not simply shoot him in the leg.
"We want a transparent investigation that clarifies the incident and clears my brother's name"
brother of Rigoberto Alpizar
Rigoberto Alpizar was the first airplane passenger shot by US air marshals since the programme was beefed up after the 11 September 2001 attacks on New York and Washington.
His coffin was laid in a crypt in Cariari's cemetery alongside his mother's remains.
US to increase marshals
Amid calls for an investigation, the US announced its Federal air marshals programme will expand their work beyond airplanes, launching what the US says is counterterror surveillance at train stations and other mass transit facilities in a test programme this week, according to a published report.
Teams of undercover air marshals and uniformed law enforcement officers will fan out to bus and train stations, ferries, and mass transit facilities across the country to "counter potential criminal terrorist activity in all modes of transportation", The Washington Post reported on its website Tuesday night, quoting documents from the Transportation Security Administration.
The Post said documents showed the teams will take positions in public areas along Amtrak's Northeast Corridor and Los Angeles rail lines; ferries in Washington state; and mass transit systems in Atlanta, Philadelphia and Baltimore.
Teams will patrol the Washington Metro system - two air marshals, one TSA bomb-sniffing-canine team, one or two transportation security inspectors, one local law enforcement officer, and one other TSA employee.
Relatives accuse US marshals of
using disproportionate force
Federal officials said there is no new intelligence indicating that terrorists are interested in targeting transportation modes, the Post said.
Rather, the Transportation Security Administration is trying to expand the role of air marshals, who have been eager to conduct surveillance activities beyond the aircraft, and provide a beefed-up presence at bus, train and other public transit stations over the busy holiday period.
"We think this is a very good approach to test our tools and quickly deploy resources in the event of a situation or a threat," the Post quoted Federal Air Marshal Service spokesman David Adams as saying. "It shows we could be at any of these places."
Some members of the team will be obvious to the traveling public and wear jackets bearing the TSA name on the back.
Others will be plainclothes air marshals scanning the crowds for suspicious individuals. It is unclear how many viper teams will be on patrol through the New Year's holiday, but air marshal officials confirm that they will be at seven locations across the country.