Authorities in central Iowa say they’ve solved a murder case that’s been cold more than two decades. Using D.N.A. evidence, capitol city police on Wednesday charged 46-year-old Martin Duffy of Des Moines with first-degree murder in the stabbing death of 32-year-old Karen Weber of Colfax. Weber’s body was found near Prairie City in 1986.

The state crime lab matched Duffy’s D.N.A., taken after a 2005 drunk driving conviction, with evidence gathered at the crime scene 21 years ago. Earlier this month, a Prairie City man was charged in a kidnapping from 11 years ago. Jasper County Sheriff Mike Balmer says they don’t believe Duffy and Weber knew each other well.

Balmer says to the best of their knowledge, Weber was someone Duffy met by chance at a nightclub in Altoona. Balmer says, "There was no real relationship at all, just a chance acquaintance." Balmer says Duffy wasn’t suspect until the D.N.A. match.

Balmer says they interviewed lots of people from the business where Weber was last seen and Duffy wasn’t one of them. Balmer says the D.N.A. hit on Duffy opened up a new avenue for them and they’ve been working for about three months since getting his name. Balmer would not say what type of D.N.A. evidence matched Duffy’s D.N.A.

It’s the second case in recent weeks that’s led to an arrest after the crime lab waded through old D.N.A. using new technology.