"Otero-Rivera appeared before an Osceola County judge Monday afternoon on premeditated murder charges. He was represented by a public defender and ordered held without bail.
Luis Rivera will not appear before a judge on first-degree murder charges Monday because he was hospitalized over the weekend, according to the Sheriff's Office.
Officials declined to provide information on Luis Rivera's condition due to federal health privacy laws.
On Sunday, Sheriff Russ Gibson said more arrests could be coming.
His next court appearance is Nov. 5.
Montalvo's twin brother, Edward Montalvo, said the family is planning a vigil for his sister Monday at the St. Cloud Lakefront at 7 p.m. Participants are asked to wear black or purple in remembrance of Montalvo and those affected by domestic abuse.
"All are invited to attend," Edward Montalvo said in a message. "We are asking any persons who have shared any memories with my twin to bring their stories and share their experiences with a community that has been touched by her liveliness. "
Vigil planned for slain St. Cloud woman; estranged husband held without bail