Police first swooped into a gas station and detained a man for questioning in the Phoenix freeway shootings. Two days later, they announced a news conference to tout arrests involving windows being shot out.

The actions briefly suggested there had been breaks in the case, but the man questioned is not a suspect, and the news conference only dealt with three teenagers using a slingshot to hurl rocks at cars and pedestrians in a suburb about 40 miles from the site of the highway shootings.

Police continue to follow leads in pursuit of the shooter, relying on everything from ballistics analysis to a robust public tip line.

Here are answers to key questions about the case:

___

WHO WAS ARRESTED?

The man questioned Friday was arrested on suspicion of violating his probation in an unrelated case by possessing a handgun and marijuana. He had been sentenced to probation just a day earlier on an endangerment charge after he fled police going up to 140 mph. Authorities are not saying what connection they believe the 19-year-old construction worker might have to the shootings. The Associated Press is not identifying him because he has not been charged or named as a suspect in the attacks.

Investigators are calling the separate slingshot arrests a copycat case involving teenage vandals accused of flinging landscaping rocks at cars and pedestrians Saturday night. The arrests received heavy media interest Sunday after the office of Sheriff Joe Arpaio promoted the "arrests made involving vehicle windows shot out." The arrests actually had nothing to do with the freeway shootings, but police cited it as an example of how the public reported suspicious activity and authorities quickly made arrests — something they want to do in the freeway shootings.

___

ARE POLICE KEEPING INFORMATION FROM THE PUBLIC?

Yes. The Arizona Department of Public Safety says it does not want to release too much information for fear of tipping its hand and potentially endangering the effort to get the shooter off the streets.

Bernard Zapor, a retired 25-year agent for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives who has investigated multiple shooting events, explained the rationale as "not providing a 'tell' to your enemy." For example, if police were to release the caliber of the bullet that has hit cars, the shooter could then carry out a new attack with a different caliber and make it harder to pinpoint a weapon.

___

BULLETS vs PROJECTILES?

Without elaborating, the department says eight cars were hit with bullets, and three were hit with "projectiles," which are typically BBs or pellets but could include rocks.

Zapor said hobbyists are known to pay more than $1,000 for air guns that can do considerable damage, using compressed air to fire pellets that can punch through metal. And he said there's always the risk of copycats using such guns to get a piece of the spotlight.

"A lot of people out there are about the age 5 intellectually and would think that would be funny," he said.

___

HOW CAN TECHNOLOGY HELP?

Tim Franklin, a former police officer and Secret Service agent who teaches at the Arizona State University School of Criminology and Criminal Justice, says several items, including drones, helicopters, microphones and sensors, can detect gunfire and help establish where it originated. Authorities also have license plate readers, and surveillance cameras cover every freeway in the Phoenix area. An examination of the bullets and where they entered the vehicles can establish whether the gun was fired from another car or an overpass.

Still, technology only goes so far, and Franklin and Zapor believe a tip from the public will be the lynchpin. "They're going to brag to a person in a bar or put something on social media. Or the public is going to catch them in the act," Franklin said.

___

Associated Press writers Terry Tang and Jacques Billeaud contributed to this report.