Ms Leahcar’s path first crossed with Mitte when they were cast members in the 2019 film Standing Up For Sunny.
The 32-year-old, who played the role of Eve in the movie, said Mitte was a “real genuine guy”, who offered her a key piece of advice during their time on-screen together.
“We met on set and he was just a lovely, engaging guy who loved a chat,” she said.
“I remember we went out for breakfast one morning and at the time I was trying out a bit of acting and asked for some advice and he said ‘you just got to act professionally and be nice to people’.
“That really stayed with me.”
Ms Leahcar, who is legally blind, said Mitte was a wonderful role model for other disabled actors and that his representation of characters with cerebral palsy was “everything”.
“As a disabled actor, you almost have to work a little bit harder to get that recognition,” the mum-of-two said.
“When I was on The Voice I didn’t realise how many people would be touched by seeing me on TV (as a blind person) and I am sure RJ had that effect in the cerebral palsy community
“That representation is everything.
“You can’t be what you can’t see.”
The singer said her thoughts were with RJ’s family at this difficult time.
“ (RJ) really did make an impact,” she said.
“He was inspiring to me …(and) I hope (his family) are remembering all the lovely memories they have with him.
“We lost a great disability advocate.”
Mitte played the lead role of Travis in Standing Up For Sunny which followed the story of the budding comedian as he finds love and acceptance through stand up comedy.
Mitte passed away at the age of 34 on Monday, local time, in Texas.
Mitte’s representatives confirmed his cause of death as suicide, according to People.