Grady Trimble and Jonathan Petramala

WTSP-TV, Tampa-St. Petersburg, Fla.

AUBURNDALE, Fla.—Thousands of people are turning to the internet for love, but one online date ended tragically for a man from Auburndale.

Police said Adam Hilarie was killed after making a connection on the dating website, PlentyofFish. Hilarie met Hailey Bustos on the dating website, and the two went on a date, then back to his apartment.

Investigators believe she was planning to rob Hilarie all along. A few hours after Hilarie took Bustos home, investigators said she returned to Hilarie's apartment with Andre Warner, Joshua Ellington and Gary Gray. After a struggle in the kitchen, it's believed Warner shot Hilarie in the head.

Hilarie was well-known in Auburndale as an amateur boxer, a good friend and a loving dad to his daughter.

“She's only five, and my God, she's just not going to be able to see how great of a guy he really is,” said Angel Cruz, Hilarie's brother.

Millions of people use Plenty of Fish and dating sites and apps like it every day. While the majority of them probably aren't using them for the wrong reasons, police say you need to be careful because some of them are.

“You just have to remember that you have no idea who you're talking to,” explained Chief Deputy Andy Ray of the Auburndale Police Department. “The person may represent themselves as one thing and be something totally different.”

Be suspicious, look people up before going on a date and don't let them know where you live, Ray said.

"Some people when they're feeling more emotional, more vulnerable, more desperate might not be thinking a hundred percent," said Dr. Nancy Wall, a certified matchmaker.

Wall, who has helped with thousands of relationships through Tampa Bay Match Makers, says people should get to know each other over coffee, not just a keyboard.

"You never really know who the person is unless you spend time with them," Wall said.

Cruz hopes other people remember the dangers of the internet so they don't have to experience the same loss he has.

"I just hate that my brother had to be the one to be an example," Cruz said.

Bustos and the three men are charged with robbery and first-degree murder. They're being held at the Polk County Jail and are expected to make their first court appearance Tuesday.

A GoFundMe page has been set up to raise funds for Hilarie's funeral.