DENVER — Colorado is investigating whether a handful of voters cast more than one ballot in the 2016 presidential election, Secretary of State Wayne Williams said Friday.

In a statement, Williams said 48 people may have either voted twice in Colorado, or voted in Colorado and in another state. Some 2.9 million Coloradans voted last fall.

Williams said the cases were discovered by local officials and during a postelection study of 11.5 million voter records in Colorado, Delaware, Maryland, Oregon and Washington.

The states planned the study well before the creation of President Donald Trump’s Presidential Advisory Commission on Election Integrity, which is investigating alleged voter fraud.

Williams said Colorado’s 48 cases were referred to law enforcement for investigation. They involve voters from both major parties as well as minor parties and independents.

In Oregon, Secretary of State Dennis Richardson said elections officials had identified 46 voters who may have cast ballots in Oregon and another state; six ballots submitted in the names of deceased persons; and two suspected cases of double-voting in the state. More than 2 million people voted in Oregon.

In Washington, Secretary of State Kim Wyman said 74 cases of possible voter fraud were referred to investigators. Nearly 3.4 million residents voted in that state in November.