The Orpo police also had sentry posts inside, where people's passes and identity cards were checked.[56] The RSD were responsible for having the Gestapo and Kripo run security checks on any employees and workers.[57] They were assisted by the SD, which investigated and monitored people for subversive activities and passed the information gathered on to the Gestapo for action when needed.[58] Wherever Hitler was in residence, members of the RSD and FBK would be present.