NEW YORK - (AP) - Investigators of the failed car bombing in Times Square are looking for a money courier they say helped funnel cash from overseas to finance a Pakistani-American's preparations to blow up the crude gasoline-and-propane bomb in the heart of New York, a law enforcement official told The Associated Press.

Investigators have the name of the courier who they believe helped Faisal Shahzad pay for the used SUV and other materials to rig up a car bomb that would have caused a huge fireball in Times Square if it had gone off, the official told the AP. The official didn't know how much money may have changed hands.

The official spoke on condition of anonymity because of the sensitivity of the investigation.

U.S. law enforcement officials traveled to Pakistan - where Shahzad spent five months before returning to the U.S. in February - to question four alleged members of an al-Qaida-linked militant group. Investigators are trying to trace his movements in his homeland and looking into the possible financing of the operation between the Pakistan-born budget analyst and foreign terror groups.

Shahzad, 30, who remains in custody on terrorism and weapons charges, lived alone in a Bridgeport, Conn., and rented an apartment with no apparent job since February. He is seen on videotape buying boxes of fireworks from a Pennsylvania store and authorities say he bought a rifle in Connecticut over the past three months with no apparent aource of income.

He paid for the used SUV with 13 $100 bills, authorities say, then tried to blow up the vehicle in Times Square on Saturday. A T-shirt vendor saw smoke coming from the SUV and alerted police.

Officials have been investigating if Shahzad got money from militant groups, including the Pakistani Taliban, which originally claimed responsibility for the bombing attempt then backed off that claim.

Story linksAccused car bomber owned Norwalk condoMuslim leaders: Shahzad not activeUB reacts to Shahzad arrestBombing suspect had several local tiesBridgeport Mayor Finch: City is safeBridgeport man charged in NYC car bomb plotBridgeport woman sold SUV used in failed attackAP source: Man tied to Pakistan sought in NYC car bomb caseOfficials: Plates on Times Square SUV from Conn.

Raw videoVideo: FBI search of home of car bomb suspectVideo: Chopper 12 footage of raid at Faisal Shahzad's homeVideo: Police raid on the Brigeport home of car bomb suspect