The man charged with killing three people at a Planned Parenthood clinic in Colorado Springs, Colorado, has targeted the agency before, his ex-wife said Tuesday.

Robert Lewis Dear, 57, could face the death penalty if he's convicted in Friday's attack, in which a police officer and two civilians were killed during a siege lasting five hours. Law enforcement officials told NBC News that after he was arrested, Dear talked about "no more baby parts" in reference to Planned Parenthood.

Dear appears to have been opposed to the reproductive health agency for decades. Barbara Mescher Michaux, who was married to Dear from 1985 to 1993, said Tuesday that Dear once put glue in the locks of a Planned Parenthood clinic near where they were living at the time — and "that was over 20 years ago when he did that," she said.

Mescher Michaux, who lives in South Carolina with her current husband, said Tuesday she was convinced that Dear specifically targeted the Colorado clinic last week.

"For him to plan this and go there, he meant to go there," she said. "There is no doubt in my mind."

Mescher Michaux said Dear "used to be a very smart man," but at some point, he became mercurial, unpredictable and violent.

"He would spin on a dime from being OK to being furious," she said. "He was abusive — very abusive emotionally, abusive physically. You never knew. It was always nerve-racking because you never knew what he was going to be like."

Related: Who Is Robert Dear?

Mescher Michaux alleged that at one point during their marriage, Dear "knocked me down and beat my head on a concrete floor."

She said she once told her current husband that had she remained married to Dear, "I felt like he would have done me deadly harm."

"I wouldn't have married him if I had known he was the way he was," she said firmly.