Simon Cowell, co-creator of One Direction and the first music producer to sign the boy band, has said the death of Liam Payne has left him feeling “empty”.

The globally successful band formed of Payne, Harry Styles, Louis Tomlinson, Niall Horan and Zayn Malik was born on Cowell’s reality show, The X-Factor, in 2010.

Together with Nicole Scherzinger, Cowell selected the boys from the groups of aspiring singers and mentored the band throughout the competition. After finishing third, the music mogul signed them to his label Syco Records where they went on to sell over 70 million records.

Following the shock death of Payne at age 31 in Buenos Aires on Wednesday, there was an outpouring of grief across the music industry and beyond. Cowell also cancelled filming for Britain’s Got Talent. He wrote on Instagram Friday: “You never really know how you feel about someone until something like this happens.”

“Liam, I am devastated. Heartbroken. And I feel empty. And I want you to know how much love and respect I have for you. Every tear I have shed is a memory of you. This is so difficult to put into words right now,” he added, saying that he went outside today and thought about the times they shared. “I wanted to let you know what I would always say to the thousands of people who would always ask me. ‘What is Liam like?’ And I would tell them you were kind, funny, sweet, thoughtful, talented, humble, focused. And how much you loved music. And how much love you genuinely had for the fans.”

Following news of Payne’s death, the former One Direction members also paid tribute to Payne writing in a joint statement, “We’re completely devastated by the news of Liam’s passing. In time, and when everyone is able to, there will be more to say. But for now, we will take some time to grieve and process the loss of our brother, who we loved dearly. The memories we shared with him will be treasured forever. For now, our thoughts are with his family, his friends, and the fans who loved him alongside us. We will miss him terribly. We love you Liam.”

Buenos Aires police said Payne’s fall from a hotel balcony resulted in “extremely serious injuries” and medics confirmed his death on the spot. The Buenos Aires Security Ministry later told the Associated Press that Payne “had jumped from the balcony of his room,” and that police responded to an emergency call warning of an “aggressive man who could be under the influence of drugs or alcohol.”

According to an autopsy, Payne died of trauma and internal and external bleeding. Officials say the death is being investigated as a “doubtful death,” according to the local prosecutor, who announced that as a matter of protocol.

Cowell’s relationship with the men since the band’s split has been scrutinized. Payne once said: “We [One Direction] were definitely overworked. I had no personal life, I learnt nothing about myself… I just lived so long as this reclusive pop star who was afraid of people, who just stayed inside all the time. I needed to stop, definitely. It would have killed me.”

Cowell has previously stated that Styles, Horan and Tomlinson had been “incredibly loyal” to him.