A serial bank robber has struck again.

The robber dubbed "Mr. Magoo" by the Federal Bureau of Investigation because of his thick glasses, may have hit at least two metro-area banks.

On Tuesday afternoon, a man matching the same description held up a US Bank at 58th and Kipling in Arvada, investigators said. This is believed to be the second strike by the man this week, said FBI agent Carl Schlaff. He also hit a US Bank in Castle Rock Monday afternoon.

In Tuesday's incident, the man handed the teller a note demanding money but did not show any signs of a weapon.

The robber is described as a 40- to 50-year-old white man, about 5 feet 10 inches tall with a medium build.

The FBI says Mr. Magoo has robbed at least 10 banks since January and has been operating since December. The agency won't release the exact number of banks that have been hit because they want him to tell them when they catch him.

However, it appears that the number of banks is climbing daily, 7NEWS reported.

He typically hits banks inside grocery stores, 7NEWS reported.

Investigators have released two surveillance photos of the man taken from robberies. The photo above was released Wednesday.