O’FALLON, Mo. — It was June, and Detective Jodi Weber was waiting at a prison in Potosi.

She had been working for 14 years to solve the brutal murders of several St. Louis women, crimes that had gone unsolved for more than three decades.

She’d read folders of investigative notes. She pulled grisly evidence out of storage. She finally had a DNA match.

And steps away was the man she’d been trying to find.

Weber, a detective sergeant with the O’Fallon police department in St. Charles County, took the Post-Dispatch inside the investigation that led her to that prison room and, eventually, to charges filed on Monday against Gary Muehlberg, 73, in the 1990 murders of Robyn Mihan, Brenda Pruitt, Donna Reitmeyer and Sandy Little.