Before the collapse of Imperial Intelligence, official service records listed thousands of Intelligence personnel as "Retired". No details, no forwarding address: simply "Retired". The vagaries of such an entry can set an imagination ablaze with theories as to what it might actually mean. Many of those theories could very well be correct.
There is ample evidence that those who had reached retirement age were sent to Medical Services for a final health examination that implemented an "electrochemical mental therapy session" to leave the retiree "free from the traumas brought on by a protracted period of service." Some whose information or abilities were deemed too valuable for such "therapy" were forcibly retired to highly secure locations like Nar Shaddaa's Shadow Town. Others still, such as the agency's former Minister, wielded enough sensitive information to hold the Empire in check and--to some extent--decide their own fates. Most, however, were likely "retired" by Intelligence in the most time-efficient, cost-effective and predictable manner possible.