Dan Wallach, associate professor of computer science at Rice University, also recommended that Colorado use paper ballots counted on scanning machines.
"Hand-marked paper ballots that are machine-scanned are the best technology that's on the market today," Wallach testified at the state Election Reform Commission meeting at the state Capitol.
Wallach has been studying voting machines since 2001 and said they are highly vulnerable to hacking. He also said machine manufacturers aren't doing enough to fix security flaws.
Despite tests that show these weaknesses, Wallach said he knew of no actual cases of tampering in elections.
The 11-member reform commission began meeting last month to make recommendations for legislation to the General Assembly by March. The group, led by outgoing Senate Majority Leader Ken Gordon, D-Denver, is analyzing a variety of issues, including voting technology, voter registration and ways to make elections more uniform.
Colorado has moved away from electronic voting in the past year. The majority of voters cast paper ballots in the last election, although a few counties still exclusively use electronic voting machines. Counties can choose their own voting systems.