As the investigation continues into the murders of seven women in Indiana, police officers in Gary used trained dogs Tuesday morning to search for more bodies while federal authorities said they believe there could be victims outside the state.

Darren Deon Vann, 43, led authorities to the bodies after he was arrested Saturday in the strangulation of a 19-year-old woman in a Motel 6 in Hammond, Ind. Over the next two days, Hammond and Gary police discovered the bodies of six other women.

Hammond Police Chief John Doughty said Vann has claimed to have killed more people going back 20 years. Investigators “have concerns” that Vann — who has lived in other states, including Texas – could have victims in other states, according to Bob Ramsey, the supervisory special agent for the FBI office in Merrillville, Ind.

“We are looking beyond Lake County and he has been cooperative,” Ramsey said, adding that local police have built a “great rapport” with Vann. “He is talking, and what we’re looking to do now is to verify some of the information that he has been providing.”

Police in Gary, meanwhile, were using trained dogs to search for bodies around the places where other women’s bodies were found over the weekend, authorities said.

“We’re just working areas, abandoned homes. Just utilizing every tool that we can,” Lake County Sheriff John Buncich said. “Nothing specific that can be pinpointed, nothing like that. Just trying to get whatever information we can, see if something turns up.”

Detectives and forensics investigators are assisting in the investigation, Buncich said. “In my 40 years of law enforcement, this is the worst I’ve seen,” the sheriff said.

A conference call among enforcement authorities was planned for Tuesday afternoon to discuss the case, Ramsey said.

Officials will discuss how the FBI might help analyze Vann’s travels over the years, determining where he lived and worked, Ramsey said. Authorities will also discuss analyzing any computers or other devices he used that might hold information, Ramsey said.

Ramsey would not say what information Vann has given but said, “The issue for us is verifying what he is providing us.”

Vann will appear in court Wednesday morning on murder and robbery charges in the slaying of Afrika Hardy, the woman found strangled at the Motel 6.

Charges in the deaths of the other women, all found in Gary, could follow soon afterward, Buncich said. He said police were awaiting autopsies and potentially more evidence. Three of them have yet to be identified.

“He [Vann] is medically cleared and placed in an isolated area away from the general population, which is not unusual when you have a high-profile case like this,” Buncich said.

When he was arrested Saturday, Vann told police he had “messed up” by leaving Hardy’s body at a motel on busy 179th Street in Hammond, where it was quickly discovered by a friend who worked with Hardy in the escort business, police said.

Vann allegedly told police about the locations of six victims in Gary, then led officers to at least some of their bodies. Vann made claims of killing an undisclosed number of other victims over the past two decades, authorities said.

It’s unclear when the six women found in Gary were killed. One of those victims was reported missing in January.

Records on Vann detail a violent past stretching back at least a decade. According to records in Texas, Vann was accused of attacking, sexually assaulting and attempting to strangle a 25-year-old woman who went to his apartment in December 2007 on a “service call from her employer.”

During the attack, Vann yelled at the woman that “he could kill her” and punched her several times in the face after she refused to give him oral sex, according to an affidavit filed with the charges. He then raped her and allowed her to leave. When she went to the hospital the next day, a nurse noted broken blood vessels in her eye and wounds on her neck and head, according to the affidavit.

DNA recovered from her clothing matched Vann, documents show.

Vann pleaded guilty of sexual assault and served five years in prison before his release in July 2013, said Jason Clark, a spokesman for the Texas Department of Criminal Justice.

While he was in prison, Vann filed a federal lawsuit against the Texas correctional system alleging his rights to due process had been violated when he was disciplined over an incident with a female guard, court records show.

Vann wrote in his 2010 complaint, which he filed without an attorney, that prison officials lied about what happened when the guard asked to see his identification card after he left the prison dining hall.

“I wish the court to reverse the displinary [sic] desecion [sic]. And to fine them for slandering my name. And also for knowly [sic] allowing a malicious and malice act,” he wrote. The suit was dismissed.

Records show Vann registered as a sex offender in Lake County, Ind., a month after his release, using an address in the 1400 block of East 50th Court in Gary.

Indiana court records show Vann was arrested in April 2004 and charged with residential entry and intimidation stemming from an incident in Gary. Police alleged he threatened to kill a man in a wheelchair over an alleged $7,000 debt that Vann believed he was owed by his ex-girlfriend, who was then living with the man, court records show.

According to court filings in that case, the victim told police he saw Vann approaching his house carrying a red plastic gas can. The man told police he confronted Vann and asked him why he wanted to “burn my family, innocent people over a woman?”

Vann replied, “Give me $7,000 and you can have her,” according to the filing. Vann also told the man that he had dynamite and would blow him up if he didn’t give up the woman, court records show.

When police arrived Vann was “holding a cigarette lighter and was acting crazy as if he might light himself on fire,” court records show.

In a deal with prosecutors, Vann pleaded guilty in June 2004 to misdemeanor residential entry, while the felony charge of intimidation was dropped, court records show. He was sentenced to a year in jail and a year of probation.

In September 2005, Vann admitted violating rules of his probation and he was sentenced to 90 days in jail, court records show.

Distributed by MCT Information Services