A shocking murder in Puerto Rico is raising concern about the safety of transgender people in the U.S. territory. Video taken just before Alexa Negron's final moments last week was posted on social media. It shows her being threatened and harassed, before gunshots are heard.

The governor of Puerto Rico said all signs point to a hate crime.

So far, her killer or killers have not been arrested.

Alexa, a 29-year-old trans woman, was harassed on social media, before her body was found with multiple gunshot wounds in Puerto Rico.

Little is known about the victim, who told people her name was Alexa. Her family isn't talking.

It appears that a false narrative was spread on social media which led people to defame her, and may have driven some to target, threaten and kill.

Alexa used the women's restroom at a McDonald's in Toa Baja, Puerto Rico. Police tell CBS News someone accused Alexa of putting a mirror under a bathroom stall to peep on people, but they say there was no proof of that.

After the McDonalds incident, people started to shame Alexa on social media. "Crazy guy dressed as a woman," one post said. "Be careful and watch out." The false narrative spread like wildfire.

"All I saw was hate, and exclusively people saying that she had to be killed," said Nandy Torres. He told CBS News lead national correspondent David Begnaud that he watched in horror as hate built on social media.

He'd met Alexa last November; he saw her lying on a bench looking scared and offered to help her. In a Facebook video he posted, he asked Alexa what was going on with her; she said she was depressed.

Alexa. Nandy Torres

"Do you have a family?" Torres asked.

"No, I don't," she replied.

"Did they abandon you?"

She nodded yes.

On the night of Alexa's murder, Torres sat at home responding to those hateful social media posts.

"I saw so much hate," he told Begnaud. "I knew in my heart that the bad was going to get to her. And at 4 a.m., they killed her."

Police told CBS News those social media posts may have motivated three 18-year-old men, who threatened Alexa and recorded it. "Look, it's the crazy woman, the crazy man. Hey, give me that ass (beep)," is heard, followed by the sound of gunshots.

In that recording, something is shot at Alexa; police are investigating whether it was a pellet gun, a paintball gun, or a handgun with a silencer.

The 29-year-old's body was found on the side of a road, shot multiple times. Twelve 9-millimeter bullet casings were found at the scene. Police believe those three teenagers left and came back to the scene, and they think they either committed the murder, or know the person who did.

Now, Puerto Rico's trans community is trying to educate people about what it means to be transgender.

Twenty-seven-year-old Maria, a trans woman living on the island, told Begnaud, "We might not be killed, but a lot of us live feeling like we are dead. We don't even have access to identify ourselves. We lose respect from our families, from our friends. We have a hard time going to the bathroom, we have a hard time getting a job, we have a hard time building a life in general."

Alexa was homeless. She had cut ties to her family, but in the end, they were required to claim her body. They had it cremated, without a funeral service.

A vigil held for Alexa. The trans woman was murdered on her 29th birthday. CBS News

Many mourners wanted a public memorial; her parents opted not to have one.

Nandy Torres said, "I want to believe that all of what has happened to Alexa, my friend, my sister, people change their way of thinking."

Begnaud asked, "What did you learn from her?"

"It's hard for me … the true pain of a human being whom I appreciated. She reignited the flame within me, the fire to keep my feet on the ground and keep trying to be a better person."

In life, it seemed that Alexa suffered silently. In death, she was humiliated publicly, and may have been killed because of an accusation that was never proven to be true.

About the mirror which someone accused Alexa of using to spy on someone in the bathroom (which the police did not find proof of), Torres said she would use it to watch her back and see who was behind her.

The Puerto Rico Police Department is leading the investigation. The FBI could open a hate crime investigation, but so far it has not.

The Human Rights Campaign says at least 26 transgender or gender non-conforming people were killed in the U.S. last year. Ninety-one percent of those cases were black women, and 81 percent involved people under the age of 30.