An Oregon man accused of killing five women has been indicted in connection with the death of a sixth woman, officials announced this week.

Jesse Calhoun was indicted by a grand jury on a charge of first-degree manslaughter in the death of Elizabeth “Libby” Gibson, said the Multnomah county district attorney on Wednesday. Calhoun is accused of causing Gibson’s death and acting “unlawfully and recklessly under circumstances manifesting extreme indifference to the value of human life”.

Gibson, who lived in Portland, was 32 when she was last seen in 2022 and reported missing the following year. Officials believe she was killed on or around 18 November 2022 but have not found her body.

Calhoun, 41, has already been charged in the killings of Ashley Real, 22; Kristin Smith, 22; Charity Perry, 24; Bridget Webster, 31; and Joanna Speaks, 32, between 2022 and 2023. He has pleaded not guilty to five counts of second-degree murder and four counts of abuse of a corpse.

“We will not stop. We will do everything in our power to hold him accountable and see that justice is done for each and every one of these victims. We remain committed to these families for as long as it takes,” Nathan Vasquez, the Multnomah county district attorney, said in a statement.

Prosecutors said earlier this year that they plan to try Calhoun for all murders in one trial rather than holding separate proceedings.

Calhoun was previously incarcerated for assaulting a police officer, trying to strangle a police dog, burglary and other charges. He was released early in 2021 for helping fight wildfires through a prison program, but Oregon’s governor’s reversed the decision in 2023 when he came under investigation for the deaths.

Gibson’s family said in a statement that they were “grateful that a definitive step toward justice is finally being taken”.

“Libby was kind, creative, and silly. She welcomed everyone with love and acceptance. Her future was tragically taken from her way too soon,” her siblings said in the statement.

“We are deeply appreciative of the tireless work and dedication of the law enforcement officers and the District Attorney’s Office whose efforts have helped bring us to this point.”

Melissa Marrero, the senior deputy district attorney, said the scope of the investigation had been “enormous”.

“But all information is useful. And to the extent that individuals have been willing to come forward in the past and provide information to us, no matter how small, that information has led us to where we are here today,” she said in a statement.