Brent J. Brents is a suspect in five sexual assaults on women and girls earlier this month in Denver — crimes committed after police said he confessed to molesting his former girlfriend's son but was released.
Police encouraged other possible victims to come forward.
"We have significant reason to believe that there are many, many additional victims," said Dave Fisher, the Denver police department's chief of investigations.
Brents was arrested late Friday in western Colorado while driving a car believed to have been taken from a woman whom he allegedly brutally beat. He was returned to Denver Saturday and held in lieu of $25 million bail.
At the rally Saturday outside a pet shop owned by one of the victims, residents shouted and shook noisemakers when a friend of the victim asked how many were angry and baffled that Brents had been freed after previous allegations against him.
"Acts of violence against women and children cannot be tolerated," the owner's fiance told the crowd.
Brents, 35, was accused late last year of inappropriately touching a former girlfriend's 8-year-old son but never arrested.
Aurora police interviewed Brents about the allegations Nov. 23, and say he told officers the boy was telling the truth.
An arrest warrant was drawn up, but it sat unsigned for over a month, reports CBS affiliate KCNC reporter Rick Sallinger. It wasn't issued until Jan. 26.
Aurora Police Chief Ricky Bennett said Brents was allowed to leave after his confession because additional investigation was needed.
Brents had been released from prison months earlier after being sent to a state hospital for about three years and then to prison for 14 years for raping a young boy and a girl.
He was linked by DNA evidence to the string of rapes in Denver, police said, and is also a suspect in an October sexual assault.
He was arrested Friday after allegedly beating a woman and stealing her car and cell phone. The victim of Friday's attack was in serious but stable condition at a Denver hospital, police said.
Police tracked calls made from the stolen phone and arrested Brents about 150 miles west of Denver. He was with a woman whom police described as a victim, but they did not immediately disclose whether she had been kidnapped.
The string of rapes in Denver began Feb. 11 with the rape of the 44-year-old pet shop owner and another woman blocks away. Brents is also a suspect in the sexual assaults on two 11-year-old sisters and their 67-year-old grandmother, according to an arrest warrant.