A small number of full episodes of Investigation Discovery shows can be found on InvestigationDiscovery.com. YouTube has a larger full episode library of Investigation Discovery series.
InvestigationDiscovery.com only has five full episodes available for viewing as of May 2015. They can be found by clicking on the "Full Episode" link on the InvestigationDiscovery.com homepage. YouTube has a large amount of full episodes that can be found using the search term #InvestigationDiscovery. Using the #InvestigationDiscovery search term will bring up all available episodes, clips and playlists listed according to popularity. Both InvestigationDiscovery.com and YouTube show one short ad before each episode.