Vonn Out of Slalom, Done With Olympics
Riesch led after the first leg and had a combined two-run time of 1 minute, 42.89 seconds through the snow and fog on Friday.
Marlies Schild of Austria was 0.43 second back to take silver.
Sarka Zahrobska of the Czech Republic trailed by 1.01 to get bronze.
Germany has won three of the five women's Alpine races after Riesch took the super-combined and Viktoria Rebensburg the giant slalom.
Downhill champion Vonn straddled a gate early in her first run and did not finish for the third time in five races.
She skied down to the finish area, smiled ruefully and was seen saying, "I don't know what's going on."
Vonn was not expected to win a medal in slalom. She struggled in the event on the World Cup circuit this season even before a series of injuries this month.
She skied with a broken right pinkie that was protected by a hard plastic casing. She also had back pain from a crash at Wednesday's giant slalom.
In addition, Vonn has been troubled by a sore right shin from a Feb. 2 training spill in Austria that prevented her practicing quick turns through slalom gates.
Vonn won two medals at Vancouver, finishing on the podium in both races she completed.
She won her gold medal as an overwhelming favorite in her signature downhill event, and took the bronze in the super-G.
Vonn crashed out of the slalom portion of the super-combined. She was poised to win a medal before failing to finish the first run in GS.
The 25-year-old American failed to complete a two-run slalom in each of her last three races before the Olympics, and had a single top-three finish in seven events this season.
Vonn last won a slalom in January 2009, at Garmisch-Partenkirchen, Germany.
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