Carson Crimeni was still breathing when his grandfather found him lying on the cement, in the dark, at a Langley Township skate park.

But after paramedics performed CPR and rushed him to hospital, the 14-year-old boy was pronounced dead.

RCMP say the teen died of an apparent drug overdose Wednesday, and investigators are now looking to speak with anyone who might have spoken to him in his final hours.

Crimeni's family said they believe someone gave the boy drugs. Witnesses stood by and captured video of the boy overdosing, they said, which was later posted to social media.

The boy was alone when his grandfather discovered him at about 9:30 p.m. PT at the Walnut Grove skate park.

"They left him to die," Darrel Crimeni said.

Darrel Crimeni discovered his grandson lying alone at a skate park. (Ben Nelms/CBC)

Crimeni said he saw some of the social media posts, including videos showing Carson in distress as others laugh and film him.

One photo, taken later in the evening, shows a young man laughing, with a caption that reads, "Carson almost died LOL."

'He wasn't waking up'

RCMP said it's believed the boy spent his last hours on foot between the Walnut Grove skate park, the grounds of Walnut Grove Secondary School and the athletic park behind the school.

The boy may have been in various parks as early as noon on Wednesday, police said.

Aron Crimeni, the teen's father, said he became worried when his son failed to return multiple phone calls earlier in the evening.

Carson Crimeni's family say the teen played hockey and loved video games. (Ben Nelms/CBC)

After waiting a few hours, Aron Crimeni called the teen's grandfather in a panic. The grandfather offered to walk around the school near his house.

"Next thing you know, I got a call from my dad saying he found him. The ambulance is working on him," Crimeni said in between sobs. "'He's in bad shape, really bad shape.'"

Crimeni raced to the hospital, where doctors gave the boy CPR. But the boy never woke up, he said.

On Thursday night, several hundred people gathered for a vigil at the skate park. RCMP members were also there to lend moral support and answer questions.

Crimeni said his son was a happy, friendly teen who played hockey and loved video games. The two often played World of Warcraft together.

People lay flowers at the Walnut Grove skate park. (Ben Nelms/CBC)

The teen struggled to make friends his age, Crimeni said, and hung out with kids who were a few years older.

"He thought these people were his friends," he said. "He trusted them."

Langley RCMP have set up a dedicated, around-the-clock tip line to gather information that might help with its investigation.

The B.C. Coroners Service is also investigating the teen's death.

Sitting in his son's bedroom, beside a soccer ball and a stack of PlayStation games, Crimeni said he's lost his best friend.

"We did everything together," he said. "I don't even have anyone else to hang out with. He's the only person I hang out with."