Christina Grimmie's alleged killer was 'obsessed' with the singer.

On 10 June 2016, Kevin Loibl, 27, allegedly shot and killed The Voice season six contestant Christina Grimmie, 22, after attending one of her shows in Orlando. Loibl then killed himself.

While we knew little about Loibl at the time of the news, TMZ has since spoken to his former colleagues at US electronic store Best Buy, who have painted a disturbing picture.

Image via Getty.

According to them, Loibl was infatuated with Grimmie and went to great lengths to ensure she wouldn't be able to resist him.

The colleagues told TMZ he'd changed his appearance for the singer, going so far as to get hair transplants and have Lasik eye surgery. He also went on a vegan diet in an effort to slim down.

Christina Grimmie auditions for The Voice. (Post continues after video.)

Loibl allegedly told his colleagues he had met Grimmie in March this year after one of her shows, though a "source close to" the singer said she had never met him. He also spoke of playing online games with her.

What's even more unsettling is the claim that Loibl vowed to make Grimmie his wife.

After seeing photos on social media of Grimmie and her producer Stephen Rezza, with whom she was rumoured to be in a relationship, Loibl's co-workers teased him about having no chance with the performer.

Christina Grimmie and Stephen Rezza. Image via Instagram.

Learning of Grimmie's supposed relationship enraged Loibl, and allegedly led to him killing her.

Our thoughts are with Grimmie's family and friends, who will be attending her funeral later today at the Fellowship Alliance Chapel in Medford, New Jersey.

Grimmie's friends have mourned her death in social media tributes: