Honolulu police suspect teenage assailants were behind three recent high-profile violent crimes in Waikiki, where hundreds of teens live on the streets.

A 16-year-old male was charged Monday with second-degree murder in connection with the death of Sgt. William H. Brown, a 23-year-old Kaneohe-based Marine who was stabbed multiple times. Police said Brown was with a group of people at about 1 a.m. Saturday at the corner of Royal Hawaiian and Kalakaua avenues when a verbal exchange escalated into an altercation.

A 21-year-old man and 15-year-old girl were initially arrested along with the 16-year-old on suspicion of second-degree murder, but have been released pending investigation.

Police are still investigating the Oct. 6 attack on a 21-year-old Schofield Barracks soldier who was beaten with a baseball bat and stabbed repeatedly. A 14-year-old boy was charged with second-degree assault in connection with the attack, which happened near the intersection of Lewers Street and Kalakaua Avenue in the wee morning hours.

Jordan Smith, 18, was charged last month with second-degree murder in the death of Maleko “Mac” Remlinger. He was also charged with one count of first-degree attempted murder, two counts of second-degree attempted murder and four firearm offenses.

Remlinger was killed Sept. 16 and two others injured when Smith allegedly used a rifle to shoot into a crowd outside Club Alley Cat.

The latest crimes have added to the Honolulu Police Department’s Waikiki load, which through September has included three murders, 24 sex crimes, 71 robberies, 339 assaults, 102 burglaries, 1,787 thefts and 209 unauthorized entries into a motor vehicle. Police don’t have the monthly statistics for October ready; however, Brown’s death has brought the year-to-date tally to four killings.

The number of Waikiki slayings is considered low compared with other urban destinations; however, Honolulu Police Department spokeswoman Michelle Yu said it’s “extremely high” for Waikiki, and for Oahu, which typically has fewer than a dozen murders a year. This year’s Waikiki 10-month murder count already has surpassed all of the Waikiki murders that occurred in 2015 and 2016.

Police, government leaders and Waikiki stakeholders say they are working to identify the crime wave’s cause, with a focus on the rash of assaults and killings. Police, who have stepped up Waikiki bike patrols and plan to assign the next graduating class of officers to Waikiki, are meeting with residents, business people and the military.

So far, police say, there doesn’t appear to be a connection among the three highest-profile incidents. However, Waikiki Improvement Association President Rick Egged and others with an interest in the tourist district say they are especially concerned about the teen involvement.

“There are too many similarities between the last two incidents involving teens and military members. Once is a problem, twice is pattern,” Egged said. “Why are these young people congregating in these hours, and what are they there for? Is it drugs, prostitution, theft or just maliciousness? Do they want to pick some sort of fight as initiation into a gang? I don’t know the answer, but these are questions that we all should be asking.”

State law prohibits unaccompanied children 16 and younger being on the streets between 10 p.m. and 4 a.m. unless they are coming from work or a school function. But Alika Campbell, program manager for Youth Outreach (Yo), a Waikiki-based drop-in center for street kids, said approximately 500 clients, youth to age 22, visited the facility about 6,000 times last year.

Nearly all are homeless — either because their families are without shelter, they’ve aged out of foster care or they are running away from a bad home situation, Campbell said. Most gravitate to Waikiki over other parts of the island because it’s exciting, without the fear factor that comes with Chinatown, he said.

It’s also more youth-friendly, and the crowd cover makes it easier for runaways, who want to escape detection, Campbell said.

“Life for them is about day-to-day survival. Where do I eat tonight? Where do I sleep?” he said. “It’s a crappy existence.”

Campbell said some street kids commit petty crimes to survive. As far as he knows, none of the teens involved in the three most recent high-profile crimes were Yo kids.

“Since police don’t release the names of minors, we wouldn’t know unless we heard it from someone. We haven’t heard anything to that effect,” he said, “but they don’t tell us everything.”

HPD’s Yu said it’s common to have large groups of young people in Waikiki, and they generally do not pose problems. Typically, Yu said, HPD receives about three to four reports a month for nuisance calls involving juveniles. However, officers have made a half-dozen runaway arrests since August and will be increasing their focus on juvenile-related offenses, such as curfew violations, she said.

Yu did not address why police needed to refocus on juvenile crime. However, HPD statistics show that last year police arrested only 51 kids for curfew violations; that’s 41 percent less than they did in 2015. Likewise, police arrested 1,417 kids islandwide on a runaway charge in 2016, which was 2 percent less than 2015.

Last year 3,717 juveniles were arrested on Oahu, but that was 13 percent less than the same period in 2015. Still, juvenile arrests jumped in four categories, including aggravated assault, which rose 11 percent to 51; stolen property, which rose 25 percent to 20; disorderly conduct, which rose 2 percent to 63; and drug law violations, which increased 5 percent to 229.

Campbell said he has got mixed feelings about cracking down on curfew and runaway violations. While it might cause some “punk kids” to go home, it could cause greater hardship for others who don’t have a safe place to return.

“It’s harder to provide outreach services when they get displaced,” he said.

Jerry Dolak, president of the Hawaii Hotel Visitor Industry Security Association, and Waikiki Neighborhood Board Chairman Robert Finley say they support greater police focus on youth curfews and runaways.

“Take the kids off the street before they develop a criminal record,” Finley said. “If we let them stay they can get victimized by adults who often use minors to assist in their crimes because they face lesser court consequences.”

Dolak said it’s a red flag when security industry members spot unaccompanied juveniles out after midnight in Waikiki — something that no responsible adult would allow.

“They are basically fugitives. They are on the run and desperate, and that’s not a good combination,” Dolak said. “They have to eat and pay for things, and they’ll do what they have to do to get money. They are angry, and they might take it out on the first person that crosses them.”