OKLAHOMA CITY - A "serial rapist with a badge" who faces many years in prison for raping black women on his police beat was caught because of the courage of a grandmother who refused to remain silent after he sexually assaulted her, her lawyer said Friday.

"He just picked the wrong lady to stop that night," said Jannie Ligons, whose police complaint triggered the investigation that led to charges Daniel Holtzclaw victimized 13 women as an Oklahoma City Police officer. "I wanted to make sure this wouldn't happen again, no way no how."

The conviction of Holtzclaw on Thursday night on rape, sexual battery and other charges should send a strong message nationwide, said attorney Benjamin Crump, who said he plans to sue the city for civil damages. "Black women's lives matter. It mattered just as if this were a group of 13 white women."

Jurors found Holtzclaw, who turned 29 on Thursday, guilty of 18 counts involving eight of the women. He was acquitted of charges involving five other women he encountered while on night patrol in a minority, low-income neighborhood. They recommended 263 years, including 30-year sentences for each of four first-degree rape convictions.

Flanked by her family and a group of African American activists outside the Oklahoma City courthouse, Ligons said she knew she had done nothing wrong when Holtzclaw pulled her over and assaulted her.

"I was out there alone and helpless, didn't know what to do. In my mind, all I could think of was that he was going to shoot me, he was going to kill me," said Ligons, a day-care worker in her 50s who was pulled over while driving home from a night with friends. "He did things to me that I didn't think a police officer would do."

Investigators found other victims through records of the background checks Holtzclaw had requested, and noticed that in many cases, the GPS locator in his squad car was switched off. He was fired and then jailed as other victims emerged.