Updated 10/21/14 - 10:16 p.m.
CHICAGO (CBS) -- A convicted sex offender was expected in court Wednesday, charged with killing one of seven women whose bodies were found in northwest Indiana over the weekend.
Police have said 43-year-old Darren Vann confessed to killing seven women whose bodies were found in Gary and Hammond, although so far he has been charged only in the strangling of 19-year-old Afrikka Hardy. Police say he also hinted there could be more.
Gary Police Chief Larry McKinley says charges will be filed within the next couple days against Vann in the deaths of three of the women found in Gary. A police source said the total number victims be much higher, perhaps 20 victims.
Hammond Police Chief John Doughty said Vann -- who is a convicted sex offender in Texas -- has been cooperative from the beginning, and told police his crimes "could go back as far as 20 years," although the victims found so far all appear to have been killed more recently.
Vann was being held at the Lake County Jail in Crown Point on Tuesday, awaiting his first court appearance Wednesday morning.
The son of a woman who was married to Darren Vann is speaking out describes the accused serial killer as a loner.
"He was just a strange guy. I walk in and I would see him talking to himself and, you know, deep thought a lot. And, she act like she'd never seen it, but I told her the guy's a nut case," said Edward Matlock.
Matlock's mother was married to Darren Vann for 16 years before they divorced.
Meantime, investigators were searching for more possible victims. Police searched Vann's home, and other buildings in northwest Indiana. The search would continue on the 4300 block of Massachusetts, where a body had been found.
Janice Williams says she often saw Vann in the area.
"I was thinking 'Oh my God! He passed by everyday. He talked. He asked for cigarettes. He'd hang out, walking pass and I never would have known," Williams said.
Gary Mayor Karen Freeman-Wilson said Vann has indicated he killed more than the seven women he's already confessed to killing. She said she hopes he keeps talking to police. Most of the victims were found in abandoned buildings, and there are 10,000 abandoned buildings in Gary alone.
Police say that they have gone through 120 buildings on Tuesday, including the Sheraton Hotel. Chief McKinley said before the hotel's demolition, there was a thorough walkthrough by employees and Gary police officers.
"Our chief feels very strongly about this. We have always been vigilant about searching abandoned buildings, but we will certainly escalate these efforts," Freeman-Wilson said.
The Cook County Sheriff's Office says it is conducting searches in southern Cook County as part of the investigation into Darren Vann.
The FBI confirmed it has been involved in the investigation from the beginning, and that Vann has told investigators there are more victims outside Indiana. The FBI was working to verify that information.
Bob Ramsey, Supervisory Special Agent for the FBI office in Merrillville, said agents were helping local authorities try to retrace Vann's steps over the past two decades, after he claimed his murders date back that long.
"Kind of start looking at the resources we could bring to the table; things like cellular phone analysis, computer analysis, development of some sort of timeline that will show Mr. Vann's travels and his residences," Ramsey said.
Police in Austin, Texas, also were looking into Vann's life there. He served five years in prison for a 2007 rape in Austin, and police there said he left Texas for Indiana in June 2013.
The FBI also confirmed Vann was in the U.S. Marine Corps from November 1991 to September 1993, when he received an "other than honorable discharge" for "minor disciplinary infractions."
Gary police started the second phase of the massive investigation around 9 a.m., using cadaver dogs to search for more bodies in vacant buildings, and wooded areas near where the bodies of six women were found over the weekend.
Detectives split up into two teams to canvass the area; searching house-by-house, looking into windows, searching collapsed garages, and even checking the burned-out shell of a house.
Gary Homicide Unit Cmdr. Tom Pawlak said the six bodies found over the weekend were found under piles of garbage or in closets inside vacant homes, so investigators must carefully check everywhere.
"We just have to go through everything; every pile of garbage, everything that he could possibly put a body at," he said.
In at least one home, police found the bones of small, dead animals, but no more human remains so far.
Investigators said they're looking for any clue that might lead them to victims whose bodies might not have been discovered yet. Police said they want to make sure there are no other victims out there.
Police were focusing their efforts on six areas in Gary, and said they will continue the search throughout the day.
Vann was arrested Saturday in Gary, a day after he allegedly arranged to meet Hardy at the Motel 6 in Hammond.
Hardy allegedly was involved in a prostitution ring, and investigators said her facilitator became concerned when she received suspicious text messages from Hardy's phone after she met Vann at the hotel. When the facilitator went to the hotel to check on Hardy, she found the young woman dead. Hardy was found naked in a bathtub, with one of her fingernails broken off, apparently as she fought for her life.
Doughty said the woman who facilitated the meeting provided investigators with Vann's phone number, and police tracked him down to Gary. When he was arrested, he confessed to killing Hardy, and told detectives he "messed up" by committing the crime in Hammond, Doughty added.
Hardy's aunt, Yolanda Mosley, said her niece dreamed of becoming a doctor,
"She was trying to get in school. She sung. She just liked to have fun. She played with the kids, her younger cousins, took them to the park," Mosley said.
Hardy's mother, who lives in Colorado, said she was heartbroken over her daughter's death.
"I can't describe her. She's indescribable. She was my rock. She was my best friend. She was my everything," Loria Townsend said.
After Vann was arrested, he allegedly told police about six other victims, and led them to the bodies, which he had left in abandoned buildings in Gary.
Three of the victims found in Gary have been identified as 36-year-old Kristine Williams, 28-year-old Teaira Batey, and 35-year-old Anith Jones. Batey and Jones were strangled. Authorities have yet to identify the three other victims.
Batey's fiancé, Marvin Clinton, said she had been missing since January. He said he heard seven months ago that Batey was dead, and her body was in an abandoned building in Gary, but police did not find her body until this past weekend, and he didn't learn Batey was one of the victims until Monday.
"Honestly, I'm pissed," he said.
Clinton said he has not yet told the 2-year-old son he fathered with Batey.
Police said Jones also had been reported missing a week before her body was found.
A source told CBS 2's Brad Edwards that the suspect has indicated that there may be many other victims, including those in other states, but Doughty said police have not confirmed any victims beyond the seven found so far.
Police said Vann raped, beat, and choked a woman in Texas in 2009, before she escaped with her life.
In 2006, Vann allegedly poured gasoline on another woman, and threatened to burn her, before police were able to subdue him.
Investigators were searching Vann's home in Gary, searching for more evidence linking him to the six murders in Gary, and any other possible deaths.
Residents in Gary were planning a prayer vigil for the victims on Wednesday night.
The Lake County Indiana Coroner is asking for the public's help in identifying two of the possible victims of suspected serial killer Darren Vann.
One of the Jane Does was found in the 400 block of 43rd Avenue in Gary last Sunday. The coroner says the woman was wearing a silver-colored linked bracelet with the words "Best Aunt" on the top of it. She was also discovered with two silver-colored rings, one heart-shaped and the other with scalloped engravings. The woman is approximately 5'3" tall, according to the coroner.
The other Jane Doe was also found last Sunday in Gary in the 4300 block of Massachusetts Street. The woman had a pair of blue jeans twenty-one black by RUE21 size 3 / 4, and white Nike gym shoes. The coroner says she is approximately 5' tall.
Anyone with information that can help identify the two women can call the Lake County Coroner's Office at (219) 755-3265.
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