Martin Kaste

Experienced gun hobbyists recognized the sound right away.

"I knew for a fact it was a bump stock as soon as I heard the video," says Jeff LaCroix. He's a recreational shooter in Louisiana. He says the rapid, uneven sound of the gunfire at the Route 91 Harvest music festival in Las Vegas last Oct. 1 made it clear to him a bump stock was involved.

Berlin's Tempelhof Field used to be a massive airport. It's famous as the site of the Berlin airlift — the effort in 1948-49 to keep West Berlin fed and supplied during a Soviet blockade. But the airport closed in 2008.

Now, 10 years later, Tempelhof Field is a huge park, and a home for refugees.

Here are some scenes, and sounds, from a recent visit.

Three years after German Chancellor Angela Merkel opened the country's borders to hundreds of thousands of migrants, the public mood toward those new arrivals has soured. In more conservative parts of the country, such as Bavaria, government officials are promising to be more "efficient" about processing migrants' asylum claims — and to deport those found not to qualify.

Unlike in the U.S., asylum claims in Germany are handled by state-level authorities — and when someone is ordered deported, enforcement usually falls to local police.

Police have always relied on data — whether push pins tracking crimes on a map, mug shot cards, or intelligence files on repeat offenders. The problem with all that information is that it has traditionally been slow and hard to use.

In the wake of the Parkland high school massacre, there's been renewed interest in "red flag" laws, which allow courts and police to temporarily remove guns from people perceived to pose a threat.

The new research offers insight into the laws' effect — and it may not be what you think.

"Although these laws tended to be enacted after mass shooting events, in practice, they tend to be enforced primarily for suicide prevention," says Aaron Kivisto, a clinical psychologist with the University of Indianapolis who studies gun violence prevention.

Updated at 4:35 p.m. ET

On a big-sky plateau on the eastern slope of the Cascades, a 10-acre parcel of land has been trashed by illicit pot farmers. Abandoned equipment rusts and jugs of chemicals molder.

Marijuana legalization wasn't supposed to look like this.

Five years into its experiment with legal, regulated cannabis, Washington state is finding that pot still attracts criminals.

You've seen it in the movies for years: Security cameras find a face in a crowd, and — Enhance! — a computer comes up with a name. In real life, facial recognition was too error-prone to work that quickly, especially with live video streams.

But now the Hollywood fantasy is coming true.

The dramatic videos of the shooting of Stephon Clark in Sacramento last month have rekindled anger over police shootings of unarmed people, often African-Americans. Many see the Sacramento shooting as a sign that little has changed in the way American police use deadly force, despite years of protests and media attention since the shooting of Michael Brown in Ferguson, Mo., in 2014.

Lately, the NRA has relied heavily on videos to communicate with the public and its supporters, and video is how it announced its position on legislation to temporarily remove guns from people thought to pose a threat.

The Parkland shooting last month has energized student activists, who are angry and frustrated over gun violence. But it's also contributed to the impression that school shootings are a growing epidemic in America.

In truth, they're not.

"Schools are safer today than they had been in previous decades," says James Alan Fox, a professor of criminology at Northeastern University who has studied the phenomenon of mass murder since the 1980s.

Investigators are blaming human error for the panic-inducing false missile alert in Hawaii last month. They say it was sent out by a state emergency management worker who mistook an exercise for a real attack.

At the same time, the incident has exposed what may be a more widespread problem: disagreement over whose job it should be to warn the public about missile attacks.

"Why did he even have a gun?" — it's a common refrain in America, often after mass shootings by people who legally aren't supposed to have firearms.

One of the worst recent examples was the massacre in a Sutherland Springs, Texas, church last November, in which 26 people were killed by a man whose domestic violence conviction should have barred him from buying guns.

The jitters over North Korea's missile tests have led Hawaii to bring back air raid sirens. The state already has sirens in place in case of tsunami, but starting this month the state will once again test the "wailing tone" meant specifically to warn of attack.

Donald W. Cook is a Los Angeles attorney with decades of experience bringing lawsuits over police dog bites — and mostly losing. He blames what he calls "The Rin Tin Tin Effect" — juries think of police dogs as noble, and have trouble visualizing how violent they can be during an arrest.

Seven years ago, a researcher named Lisa Lit published a study that she now calls "a real career-ender."

Any American who pays attention to law enforcement has heard of the strategies: "broken windows," "stop and frisk," "zero tolerance." These are all variations on what's broadly known as "proactive policing": efforts to seek out and prevent the causes of crime before it happens, as opposed to a more reactive policy of just sending police when called.