(Oregon City, OR) -- After a ten year investigation, a Molalla man has pleaded guilty to sexually abusing his adopted sisters. They were all younger than ten at the time. Dennis Fleck is now 34. Fleck was investigated in 2013, but there wasn't enough evidence to charge him with a crime, and only one of the girls disclosed abuse back then. But in 2022, the detective re-opened the case when he learned the other two sisters had also been abused. Fleck pleaded guilty to three counts of first-degree sex abuse.