They carried signs calling for justice, hoping someone will help the family find the answers they've been seeking for months.
"Regardless of the wait, we will not rest," said James Faust, Baldelli's father. "Whoever took Yvonne from us needs to be behind bars."
Baldelli, a former Dana Point resident, left California last September. Relatives said she was newly divorced and starting a new life in the province of Bocas del Toro on Panama's Caribbean coast.
She traveled to Panama with her boyfriend, 36-year-old Brian Brimager, and they shared a home.
Baldelli disappeared in late November. According to her family, the case is now being investigated as a homicide.
They're hoping anyone who has visited Panama may have information that will help investigators. They also want the public to write to lawmakers asking for support.