In the 1976 film "All the President’s Men," the shadowy character played by Hal Holbrook famously asserted that the key to unraveling the Watergate scandal that was enveloping Richard Nixon’s presidency was to “follow the money.”

Forty-four years later, the money trail is a key part of investigations that are dominating headlines in the Trump era.

Former Trump campaign chair Paul Manafort is on trial and the office of former Trump lawyer Michael Cohen was raided, all while special counsel Robert Mueller continues to investigate whether the Trump campaign had any connection to Russia's attempt to interfere in the 2016 election. Some of the probes involve the president directly, while others could be used by prosecutors as leverage to secure the cooperation of Trump confidants.

As investigators dig deeper, they are focusing attention on banks that have facilitated transactions for various people in Trump’s orbit. Here is a look at some of the banks that have been pulled into Trump-related probes.