Terrence Coulter, 33, faces murder charges in Hayes' death. The south suburban mother disappeared in January and her decomposed body was identified by DNA two months later. It was found in a field in south suburban Thornton on March 23.
Police say Coulter is Hayes' estranged boyfriend and she was supposed to testify against Coulter after he allegedly tried to kill her in 2007. Hayes was stabbed more than a dozen times with a paring knife while arguing with Coulter in a car in Riverdale.
Hayes family said she was involved in an on-again/off-again abusive relationship with Coulter for 13 years.
"It's sad but I think justice will be serviced now. its a big burden lifted that they did charge him," Dorsey Hayes, the victim's brother, said.
Prosecutors said Coulter murdered Hayes to keep her from testifying against him in the trial for the 2007 attempted murder case.
"This is a tragic case involving a senseless murder of a victim of domestic violence who was struggling to break away from a relationship with a violence man," said Anita Alvarez, Cook County state's attorney.
The 35-year-old single mother was last seen at school dropping off her 16-year-old son, who told investigators Hayes had planned to see Coulter later that day at an area motel. Hayes had an order of protection barring him from contacting her.
"We can't speak on if she went willingly, if he threatened her," said Robbie Thomas, victim's niece.
Authorities say Coulter rented a room at a South Holland motel on January 24th and 25th. During that time, officials said he beat and strangled Hayes. Motel workers confirmed seeing them together and police say they found physical evidence-- including Hayes' blood. Her car - a 2005 Kia Spectra- was found days later less than a mile from there.
"She moved from Riverdale to Park Forest to get away from around all that type of stuff," said Lenn Thomas, victim's nephew.
Advocates against domestic violence said Hayes' death proves victims need more help.
"We need to change the focus. What was the abuser doing? What did anyone do to try to stop him from using violence in his intimate relationship," said Dawn Dalton, Chicago Metropolitan Battered Women's Network.
Hayes' family members said they hope her death brings changes for other victims of domestic violence.