"We said a prayer for her so that we can get some kind of closure," said Michelle Perez, a family friend.Friends, coworkers and family members released balloons with heartfelt messages on Sunday at El Dorado Park in Scottsdale for Rivas.
"I loved her and I will do her proud," said Perez.
Rivas was reported missing on June 8.
Her boyfriend, Rolland Camargo, was taken into custody Friday after admitting he dumped her body on a farm in Pinal County. But, he did not admit to having any part in her death.
Perez says their relationship was rocky.
"We all knew the minute that Nicole went missing, we had our ideas of him being a part of it in one way or another," said Perez.
The group came to find closure and celebrate Nicole's life on Sunday.
Former McDonald's coworker Angela Escobar says she and Rivas formed a quick friendship.
"She became like a mother to me and there was times where my mom couldn't be there for me and she was always giving me advice," said Escobar.
Escobar says she was also a loving mom to her 5-year-old daughter.
"Just really hard. She didn't deserve it. She was a really good mother and her daughter was her world and it's just not fair that she has to grow up without her now," said Escobar.
As their messages were sent up to Rivas, they await answers.
"How she passed and why, why her?" said Perez.
Camargo is charged with abandoning a body. For now, police are calling it a suspicious death.