As @DavyJack said, press F2 to bring up the interface screen. Scroll through the characters to your chosen officer. Now click the "Inventory" tab as if you were looking at your own inventory; instead, you'll be looking at the officer's inventory.
Alternatively, walk up to your officer and press Enter. There should be a line of icons at the bottom of the screen, among which are one to talk and one to trade items. You can then exchange items between the officer's inventory and your own.
Alternatively, walk up to your officer and press Enter. There should be a line of icons at the bottom of the screen, among which are one to talk and one to trade items. You can then exchange items between the officer's inventory and your own.