KANSAS CITY, Mo. — As a felon, F. Glenn Miller Jr. had no legal right to a gun.

What’s more, a gun dealer would face prison time for selling him a weapon.

Even a friend who gave or sold him guns would risk federal prison time for arming someone they knew or suspected was a felon.

Yet the proud racist and anti-Semite stands accused of firing a shotgun and a handgun in the murder of three people at Jewish facilities in Overland Park last weekend.

So who put his finger on a trigger?

Investigators tracing the source of the guns allegedly used by the felon think he was aided by a straw buyer who could clear background checks likely to foil Miller, said a law enforcement official familiar with the case.

The law enforcement source, who insisted upon anonymity because of the sensitivity of the matter, said local police and agents from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives are trying to locate the middleman.

Such a gun-buying go-between represents a vexing problem for keeping firearms out of the hands of people like Miller who lost their Second Amendment rights when they became felons.

Gun rights advocates blame lax enforcement, not firearms law, for the problem. After all, investigators are pursuing a lead on what would already be a federal felony.

“Most criminals obtain guns from theft, the black market, or ‘straw purchasers,’” the National Rifle Association says.