MIDTOWN — A ripoff involving hundreds of thousands of dollars worth of cocaine from Mexico was the motive behind the brazen execution of Los Angeles law student Brandon Woodard in the heart of Midtown earlier this month, DNAinfo.com New York has learned.

Law enforcement sources said that the killers — believed to be part of a Queens drug crew — paid "a substantial amount of cash," but never received their shipment of cocaine from the West Coast and were fed up waiting for it.

Woodard was lured to his death on West 58th Street near Seventh Avenue where he was shot in the back of the head in broad daylight.

Sources said the federal Drug Enforcement Administration has joined the probe, considering the bicoastal aspects of the slaying, and its ties to other violence and murders.

"It is really not a homicide investigation," one source said. "It has become a major narcotics case involving a big operation and substantial money, perhaps millions of dollars."

The DEA is providing intelligence and resources to the NYPD about drug trafficking here and on the West Coast, and into possible connection reaching to drug distributors out of the nation of Jamaica, sources said.

Meanwhile, sources told “On the Inside” the NYPD is getting closer to identifying the cold-blooded killer who calmly pumped a bullet from a .9mm handgun into the back of Woodard’s head as he was lured to his death last week.

The NYPD has already identified the driver of the getaway car, DNAinfo.com New York previously reported.

Authorities suspect both the killer and the driver of the rented Lincoln MKZ are low-level Queens thugs with arrest records for drugs who are part of a powerful crew whose members they are trying to identify.

Neither of the possible suspects has been picked up and questioned as authorities are taking their time gathering evidence to make sure they have a strong case against them and that no false steps are made.

Woodard, who also has a lengthy criminal record including for dealing cocaine, was apparently a middleman or courier in the drug deal that went bad, sources explained.

“The Los Angeles guys thought they were tough, and could f--- with the boys from New York,” one source told “On The Inside.”

They were dead wrong.

“They screwed with the wrong people,” the source said.

"These guys move a lot of money and a lot of product," another source said.

DNAinfo.com New York previously reported that Woodward’s killing had ties to several other murders and shootings.

One of three cellphones found on Woodard was linked to a Brooklyn club promoter, who was an acquaintance of three men who were assassinated earlier this year after a party.

Those victims, each packing guns, were lured to a Queens schoolyard and executed in a fusillade of AK-47 automatic gunfire as they sat in a Jeep.

Investigators believed those killing had ties to marijuana and possibly cocaine trafficking out of the island of Jamaica — and the DEA is also providing intelligence related to Caribbean traffickers.

In addition, a single shell found at the West 58th Street crime scene matched bullets sprayed into a Queens home in 2009. A man who lived there at the time — and was a possible target — was involved in a fight on Staten Island earlier this year. A few days later, his attacker with was shot and killed.

Woodard’s brutal assassination was captured on several videos that were released by the NYPD. Images of the Lincoln getaway car were later captured heading into Queens from the Queens-Midtown Tunnel, police said.

The woman who rented the car told investigators she gave it to another man, who in turn insists he lent it to someone else. Neither is considered a suspect.