SAN JOSE — An eagle-eyed police sergeant helped investigators swiftly recover an AR-15 rifle and another handgun stolen during a recent home-invasion robbery in San Jose, and when they zeroed in on the suspects, a telltale T-shirt sealed the case.

Video surveillance of one suspect, a 17-year-old boy, showed him wearing a distinctive “Billionaire Boys Club” shirt, part of a hip-hop themed clothing line by music producer Pharrell Williams. When police served a search warrant at the teen’s home, they reportedly found the same shirt, not far from where they found the stolen rifle.

Besides lauding the bust, San Jose police are highlighting the case to renew attention on a continuing rise in violent crime involving juvenile suspects in county — as outlined in a recent prosecutors’ report — and to illustrate a local trend of violent intruders blurring conventional distinction between burglars and robbers.

It’s common for people to use the terms interchangeably, but burglaries and robberies are distinct. Burglaries do not involve confrontation — think the elusive and undetected cat burglar — while robberies involve force or the threat of force.

What that has meant in the past, says SJPD robbery Lt. Paul Joseph, is that the people committing each crime displayed opposite traits: those who avoided contact and those who were fueled by it.

“The burglar was about getting in and getting out, while the robber seemed to enjoy the confrontation,” Joseph said. “Now we have burglars who are armed and show no reluctance to shift gears.”

If burglars realized someone was home, they would leave and look for another target.

“Now when they’re interrupted, they have no problem confronting people,” Joseph said. “I don’t have an explanation for this shift.”

That appeared to be the case May 29, when the 17-year-old suspect, along with a 19-year-old accomplice, entered a home on Woodbury Court in the Evergreen area. But when they realized it was occupied, police say they forced the homeowner at gunpoint to open a gun safe. The intruders took an AR-15 and a Sig Sauer pistol, along with cash and jewelry, police said.

Before the pair escaped, however, home-security cameras captured images of their getaway car, which were distributed to patrol officers in the city. Within days, Sgt. Rick Foster spotted a matching vehicle near Kammerer and Sanders avenues in the Mayfair area, and police impounded the vehicle.

Inside, investigators found the stolen Sig Sauer, and other unspecified evidence that Joseph said led to the identification of the two suspects. On June 1, police found them in another car near 19th and East Santa Clara streets and arrested them. The 17-year-old was reportedly carrying another stolen handgun when he was taken into custody.

The 19-year-old suspect was identified as Oscar Vazquez of San Jose, while the 17-year-old’s identity was withheld because he is a minor. Police served search warrants at both of their San Jose homes, and at the home of the younger suspect, they found the stolen AR-15, Joseph said, along with the “Billionaire” T-shirt.

Joseph said that robberies and carjackings in San Jose involving juvenile suspects are up 19 percent compared to the same point last year, from 123 cases to 146. Two more detectives were recently added to the department’s robbery unit, bringing the outfit to eight officers and two sergeants, taking on a daunting task in a city of a million residents.