At the time of is termination, Comey was leading the FBI investigation into Trump's campaign and possible collusion with Russia.
In a Twitter post yesterday, Trump now claimed that "Lester Holt got caught fudging my tape on Russia," meaning he's saying that he never admitted to obstruction of justice and that Holt doctored the interview tape (details here).
This is such a ridiculous lie it's pathetic. One simply need look at the tape and watch Trump's mouth moving when he says that. As well, an electronic forensic analysis can easily prove the tape was not altered.
The fact that Trump brought up the Holt interview more than a year later suggests he knows it's highly damaging because he admits to a crime. This suggests he's been talking to his lawyers about the topic and something might be in the wind. Stay tuned.