That was never proven. A key reason why that was never proven was because a proven, as in proven beyond a reasonable doubt and convicted, corrupt federal agent had access to everything needed to fabricate the extremely limited evidence they used to insinuate it.
Do you know how rarely LEOs getting convicted of anything? If there wasn't a mountain of evidence that Ulbricht ran the silk road, the entire case might have been rereparable tainted.
Why would they fabricate such evidence?