A Suffolk Superior Court jury today convicted a former South End man for a pair of rapes he committed more than 20 years ago, setting the stage for a potential life term, Suffolk County District Attorney Daniel F. Conley said.

After deliberating for about two hours, jurors convicted MICHAEL JOHNSON (D.O.B. 4/9/69) of rape, aggravated rape, and assault with intent to rape for his attacks on three South End women during the spring of 1990.

“This was a complex case with a great deal of scientific testimony, but it could not have been made without the women who reported these attacks,” Conley said. “They called police. They went to the hospital for rape kits. They testified at trial knowing how difficult it would be. Their assailant was identified through DNA, but their strength made these convictions possible.”

During the week-long trial, Assistant District Attorneys Leora Joseph and Barbara Young proved that Johnson broke into a Wellington Street apartment on the morning of April 10, 1990, and raped the 23-year-old woman who lived there after binding her hands behind her back and covering her face with a towel.

They also proved that Johnson broke into a West Concord Street apartment at about 1:00 a.m. on May 7, 1990, and held two women, ages 24 and 30, at knifepoint. He raped one and tried to rape the other but was physically unable to do so. That second victim then struck Johnson with an iron fireplace poker, prompting him to flee the apartment.

In the aftermath of the separate attacks, all three women went to area hospitals, where biological evidence was recovered and logged in sterile rape kits that were stored at the Boston Police Crime Laboratory.

In 2003, Boston Police and Suffolk prosecutors undertook a project that re-examined unsolved sexual assault cases that had DNA evidence, which was newly-admissible in Massachusetts courts. Among those cases were the April 10 and May 7 attacks. The DNA evidence in those cases was uploaded to CODIS – the nationwide Combined DNA Index System database – and, in September 2003, matched each other and Johnson’s DNA profile.

Johnson’s DNA profile was in the database from a 1999 home invasion for which he was convicted in March 2003 and for which he is still serving a 33- to 40-year prison sentence. He was subsequently indicted by the Suffolk County Grand Jury.

“The passage of time doesn’t affect our commitment to these cases,” Conley said. “This was a violent predator. He had to be held accountable.”

Anne Kelley-McCarthy was the DA’s victim-witness advocate on the case. Johnson was represented by attorney Bruce Carroll. Judge Peter Lauriat will sentence him tomorrow at 2:00 p.m. in courtroom 906 of Suffolk Superior Court.