OPM breach may have been the work of hackers with ties to Chinese espionage agencies. The OPM hack may have put federal employees at greater risk of being recruited or coerced by a foreign power. “The Chinese know [now] everything the [government] learned,” an operational security expert known as the Grugq says via Twitter. Many government agencies only retain logs for 60 days, and government investigators believe that the breach started a year ago. As a result, details of the initial intrusion and 10 months of data exfiltration may be lost.”]
Source: https://www.cuinfosecurity.com/analysis-opm-breach-so-bad-a-8359