GARY, Ind. -- With hindsight, there were signs years ago of increasing violence against women by Darren Vann, who police said Tuesday has confessed to killing seven women in Indiana.

Indiana court records from 2004 describe him grabbing a woman in a chokehold, dousing her with gasoline and threatening to set her on fire. He was sentenced to a year in prison for that incident.

In 2009, he was convicted in Texas of raping a woman. She told police that when she went to his apartment in Austin he knocked her down and began to strangle her, hit her several times in the face and said he could kill her, court records show. He served time in prison until last year, when he was released and moved back to Indiana.

In both cases, the charges against Vann were reduced as part of plea bargains, and Texas officials deemed him a low risk for violence. He registered as a sex offender in Indiana and police made a routine check in September that he lived at the address he provided.

"He was not on our radar at all," Gary Police Chief Larry McKinley said at a news conference Tuesday, adding that Vann was never suspected of taking part in murders in the days or months before his arrest.

Now, Vann has been charged with the strangulation death of one woman, and authorities in two states are poring over cold case files and missing person reports to determine if there are more victims. Vann has confessed to all 7 of the killings in Indiana, McKinley said, and more murder charges are expected in a few days. He will appear in court Wednesday for the first time since his arrest over the weekend.

Several families who have missing relatives have called since the bodies were discovered to ask if their loved ones might have been killed by Vann, said another Gary officer, Commander Del Stout.

Family and friends of victims said police should have known the 43-year-old Vann was a threat and taken reports of women disappearing more seriously.

Victim Teaira Batey's mother, Gloria Cullom, said she called Gary police constantly looking for information about her daughter and never heard back.

"I'm trying to find out, 'Have you heard anything. Do you have any information for me?' Nobody ever called me back," Cullom said.

The family filed a missing person report on Batey in late January after she had been missing for nearly three weeks.

Cullom told police her daughter suffered from schizophrenia, was HIV positive and had a cocaine habit. She had last been seen leaving with a male friend she called Popeye.

Clinton said the family knew "something had gone terribly wrong" when they didn't hear from Batey, who has a 2-year-old son with Clinton and had given up prostitution several years ago to focus on being a mother.

McKinley on Tuesday defended police handling of the reports.

"We take every report seriously," he said.

Vann appeared to keep a low profile and follow the rules after serving a prison sentence for sexually assaulting the woman in Austin.

He registered as a sex offender in Indiana in July 2013 after he moved to Gary, said Patti Van Til, a spokeswoman with the Lake County Sheriff's Department.

Vann registered again in Indiana this past July, putting him in compliance with a state law that calls for sex offenders to re-register at least once each year, she said.

Detectives with the sheriff's department last checked on Vann on Sept. 14 to make sure he was living at the Gary address listed on the registry.

"He had registered and complied with the requirements," Van Til said. "We had the appropriate response from him."