The money, sent on behalf of South Africa, was meant to be used for its Caribbean diaspora legacy programme.
But documents suggest Mr Warner used the payment for cash withdrawals, personal loans and to launder money.
The 72-year-old, who has been indicted by the US FBI for corruption, denies all claims of wrongdoing.
Fifa says it is co-operating with the investigation.
And South Africa’s Football Association has issued a detailed statement denying any wrongdoing.
The papers seen by the BBC detail three wire transfers by Fifa.
In the three transactions – on 4 January, 1 February and 10 March 2008 – funds totalling $10m (£6.5m) from Fifa accounts were received into Concacaf accounts controlled by Jack Warner.
At the time, he was in charge of the body, which governs football in North and Central America and the Caribbean.
The money had been promised by South Africa’s Football Association for its so-called diaspora legacy programme to develop football in the Caribbean.
The documents reveal how the money was spent and moved around.
JTA Supermarkets, a large chain in Trinidad, received $4,860,000 from the accounts.
The money was paid in instalments from January 2008 to March 2009. The largest payment was $1,350,000 paid in February 2008.
US prosecutors say the money was mostly paid back to Mr Warner in local currency.
The BBC gave details of its investigation to Brent Sancho, Trinidad and Tobago’s sports minister and a former footballer.
He said: “He [Mr Warner] must face justice, he must answer all of these questions. Justice has to be served.
“He will have to account, with this investigation, he will have to answer for his actions.”
The documents also show $360,000 of the Fifa money was withdrawn by people connected to Mr Warner.
Nearly $1.6m was used to pay the former Fifa vice-president’s credit cards and personal loans.
The documents show the largest personal loan Mr Warner provided for himself was $410,000.
The largest credit card payment was $87,000.
Mr Sancho says he is now angry and disappointed.
“I’m devastated because a lot of that money should have been back in football, back in the development of children playing the sport.
“It is a travesty. Mr Warner should answer the questions,” he added.
‘The gloves are off’
Jack Warner is one of 14 people charged by US prosecutors over alleged corruption at Fifa.
The US Justice department alleges the 14 accepted bribes and kickbacks estimated at more than $150m (£97m) over a 24-year period.
Mr Warner denies all charges of corruption.
(Selorm) | 
(Nana Kwesi)