(This story corrects to “private” from “gun store” to clarify type of sale in paragraph 4 in April 26 story.)

FILE PHOTO: Metro Davidson County Police inspect the scene of a fatal shooting at a Waffle House restaurant near Nashville, Tennessee, U.S., April 22, 2018. REUTERS/Harrison McClary

(Reuters) - When Travis Reinking’s semi-automatic rifle was confiscated after his attempt to enter the White House last year, he simply moved from Illinois to nearby Tennessee where signs of mental illness are no bar to gun ownership.

How and when Reinking’s father returned the AR-15-style weapon and other firearms to his 29-year-old son, accused of shooting dead four people and wounding four at a Waffle House restaurant in Nashville, Tennessee remain unclear.

Confusing as well are the myriad of U.S. state gun laws that can make it difficult to stop crimes like Sunday’s mass shooting.

The U.S. federal system leaves it up to states to set most gun laws. Less than half of U.S. states require background checks before private sales, and only a small number require “universal checks” for all purchases, including at gun shows.

Virginia has improved mental health reporting after a 2007 college campus massacre but has no laws requiring firearms to be registered. Alaska, with the highest state rate of gun deaths per capita, does not allow firearms to be registered. Most states let residents carry firearms in public, and all states permit the carrying of concealed weapons in some form.

The assault on Sunday is the latest mass killing to stoke a fierce debate that pits gun control proponents against gun rights advocates who defend constitutional rights to own guns.

The debate has sharpened since the Feb. 14 shooting at a Parkland, Florida, high school. That massacre prompted an upsurge of teenage gun control activism, including a nationwide student walkout on April 20, two days before the Nashville shooting.

The discussion has aired demands for national laws that would provide uniformity, including regulations on the transport of guns from state to state, as with the Reinking case.

“We need to have national laws that protect against these over-the-border kinds of transfers,” said Illinois state Representative Kathleen Willis, a Democrat who is sponsoring “red flag” legislation to let family members request the seizure of firearms from relatives facing mental health problems.

MENTAL ILLNESS

The variety of ways that gun laws address mental illness has prompted concern. A study by Mother Jones magazine showed that in 62 mass shootings between 1982 and 2012, 38 of the shooters displayed signs of mental health problems before the killings.

Reinking himself has a troubled past. He believed that pop singer Taylor Swift was stalking him and threatened to kill himself, according to police records.

The National Rifle Association, the country’s most powerful gun-rights lobbying organization, says it supports legislation to ensure records of those judged mentally incompetent or “involuntarily committed to mental institutions” be made available for use in firearms transfer background checks.

“The NRA will support any reasonable step to fix America’s broken mental health system without intruding on the constitutional rights of Americans,” the group says on its website.

That support stops short of legislation like Willis’ red flag bill with its “insinuation that gun ownership makes you a danger to yourself or others,” the group said last month.

Illinois is unusual in giving law enforcement the right to revoke a gun license and take away guns from persons if their mental health appears to pose a danger. In Tennessee, like most states, police can only seize guns if a person is involuntarily committed to a mental health facility and judged a danger. Even then, the owner can keep their firearms.

In Reinking’s case, Illinois state police revoked his gun license, and his firearms were transferred to his father after U.S. Secret Service agents arrested him last year for being in a restricted area near the White House.

Authorities have not disclosed whether his father gave him back his guns in Illinois, where it would likely be a crime, or in Tennessee, where it would not.

The U.S. Congress has not passed any substantive national gun laws since the 2012 Sandy Hook massacre, due in large part to opposition from gun-rights groups.

Yet some gun-control advocates see steady movement towards uniform gun laws through actions at the state level.

“Our movement is chipping away and convincing lawmakers that they should be voting for public safety,” said Jonas Oransky deputy legal director of gun control group Everytown for Gun Safety.

For example, after the Waffle House shooting, Tennessee lawmakers drafted legislation to make it illegal to buy or possess a gun if a person had been subject to “suspension, revocation or confiscation” in another state.

For Illinois lawmaker Willis, it is too little too late.

“All the red flags were there. They followed all the gun laws in Illinois,” she said. “Until we have national laws to restrict this, it’s not going to stop.”