A convicted predatory sex offender from Minnesota, Rodriguez is now charged with kidnapping in the disappearance of University of North Dakota student Dru Sjodin.
The 22-year-old was last seen in the parking lot of a Grand Forks, N.D., shopping mall where she worked at the Victoria's Secret store. That was on Nov. 22, and except for two calls placed from her cell phone that same day, there has been no trace of her since.
"Our community is a safer place this morning," said Grand Forks Police Chief John Packett in announcing the arrest.
"We do have probable cause that he was in Grand Forks at that time and that he was in the parking lot," state's attorney Peter Welte said.
Alfonso Rodriguez's release from a Minnesota prison last summer after serving 23 years for sex offenses alarmed his hometown. He could have been kept confined for more treatment but the state chose to release him.
"He was then 50 years of age and most of the data shows that recidivism is less likely the older the offender gets," said Minnesota Corrections Commissioner Joan Fabian.
For years, debates have raged across the country about what to do with sexual predators - and whether they're ever really cured.
Today, all 50 states require convicted sex offenders to register with authorities so the public knows that a potentially dangerous offender lives in their neighborhood.
At least 16 states have violent sexual predator laws that allow them to lock up sex offenders and force them into treatment once they've completed their prison sentence.
In Texas, police often find registered sex offenders deliberately listing phony addresses. Records show the state has no idea where more than 7,000 sex offenders really are.
One convicted pedophile says he can't be cured: "One thing that you don't take away from a sexual offender, while he's in prison, is his urge and his fantasies."
An angry Minnesota governor wants maximum penalties.
"I've had it with sexual predators," says Gov. Tim Pawlenty. "The death penalty should be an option for juries to consider in these cases."