Charlie Puth dedicated See You Again to Christina Grimmie at his concert.
The 24-year-old singer - who originally recorded the song with Wiz Khalifa as a tribute to actor Paul Walker - performed a stripped down version of the track at his New York concert in memory of his friend Christina, 22, who was shot dead by a man police believe was a deranged fan the night before.
He said: "I was reading the news last night and heard that my good friend Christina Grimmie was killed, and I want to dedicate this song to her tonight. I've been upset about this all day, mainly because I just never got to say what I wanted to say to her, and I feel like this song perfectly captures that."
Earlier, Charlie had tweeted about Christina, writing: "When you die, your body dies, but your soul lives on forever, as will hers. Rest In Peace Christina Grimmie. A beautiful talent.
"At the end of the day, we laugh, we cry, we dance, and we sing together."
Christina had opened for the band Before You Exit at The Plaza Live in Orlando and stayed on afterwards to sign autographs for fans when Kevin James Loibl - who was carrying two handguns, two loaded magazines and a hunting knife - approached her and opened fire.
During a press conference Orlando Police Chief John Mina said it was likely that the man was a deranged fan and that Christina did not know him.
He said: "That would be speculation, but that's what it's looking like.
"There's no indication that he knew her, we're looking into that to try and find a motive for the crime."
He added that police were currently searching through the Loibl's phone and computer to find a possible motive for the murder.
Police believe Loibl travelled to the gig with the intention of killing Christina.
The police chief added: "He came here to commit this crime and had plans to travel back to where he came from."
However, after Christina's brother tackled Loibl, the murderer killed himself.
- Bang! Showbiz