New York mayor sent investigators to Phoenix, Arizona – where they were able to buy Glock pistols with no questions asked

Undercover investigators have exposed the ease with which high-powered guns can be bought in the US, purchasing the same type of pistol used in the Tucson massacre just two weeks later in a neighbouring city – with no questions asked.

New York's mayor, Michael Bloomberg, sent a team of undercover agents to the Crossroads of the West gun show in Phoenix, Arizona, just 120 miles away from the scene of the Tucson shooting. There, on 23 January, they bought a Glock 9mm pistol of the kind wielded by Jared Loughner when he killed six people and wounded 13, including the US congresswoman Gabrielle Giffords, at a public meeting in Tucson.

The agents filmed the gun sales using hidden cameras.

They bought a Glock 17 gun for $480 (£299) and three $40 extended magazines each holding 33 bullets. Loughner had a 33-round extended magazine attached to his Glock 19, allowing him to wreak carnage in Tucson by shooting multiple times.

The New York investigators bought the gun with no questions asked other than the requirement of an ID card.

Under current federal law, that sale was legal because of the so-called "gun show loophole" that allows occasional gun sellers to trade weapons without carrying out a background check to ensure that the purchaser is not mentally ill, a criminal, or a drug abuser. Such "private" sales are responsible for 40% of all gun sales in the US.

Of less certain legality was the purchase that the New York investigators went on to make of a SIG-Sauer SIG Pro 9mm pistol for $500, and a Smith & Wesson for $450. In both cases, the undercover agent admitted to the seller that they "probably couldn't pass a background check".

Under federal law even private sellers are not permitted to sell guns to any individual they "know", or have "reason to believe", is not eligible to own a gun.

The video footage of the sale of the SIG-Sauer gun shows the investigator saying he wants to buy a weapon with "stopping power ... that's concealable. You know what I mean?"

The seller appears to be complicit in the idea of disguising the purchase when he replies: "The good thing is, if you don't like it, you can just sell it later and it's not in your name."

The seller demands only the production of an ID card to go ahead with the purchase, and the investigator then says: "So, no background check?"

The seller replies: "No."

Investigator: "That's good because I probably couldn't pass one, you know what I mean?"

The seller says nothing, and the sale goes ahead.

Bloomberg released the video on Monday, saying: "We have demonstrated how easy it is for anyone to buy a semi-automatic handgun and a high capacity magazine, no questions asked."

The undercover operation was a repeat of a sting that New York carried out on gun shows in Nevada, Tennessee and Ohio in 2009. That exercise found that 63% of the gun sellers approached were in breach of federal law by willingly selling guns to people who admitted they probably wouldn't pass a background check.

In the case of the Tucson shooting, Loughner did pass background check before he bought the Glock 19. However, he only managed to do so because the US army, which rejected him because of his history of drug abuse, failed to pass on that information to the FBI's national database.