The phrase "almost certainly guilty" is correct and usable in written English.
It can be used in contexts where you want to express a high degree of likelihood regarding someone's guilt in a situation, often in legal or moral discussions.
Example: "The evidence presented in court suggests that the defendant is almost certainly guilty of the charges against him."
Alternatives: "highly likely to be guilty" or "very likely guilty".
But he is almost certainly guilty of cowardice and hypocrisy.
Although Smith was almost certainly guilty, Spilsbury's intense self-belief – and the implicit faith invested in him by the legal system – also led to several miscarriages of justice.
Adnan Dayoub, a rebel commander in Hama, said that General Shallal had been responsible for prisons — "God knows how many," he said — and was almost certainly guilty of crimes.
She was almost certainly guilty of ordering the killing by her "football club" of her own doctor and devoted supporter, Abu-Baker Asvat, when he was subpoenaed to give evidence after he examined Stompie shortly before his death.
Frobisher seems almost certainly guilty of the crimes he is being accused of and yet you can't help but fall for his good looks, cocky asides and vicious sense of fun.
Here too, the Simpson trial was 20 years ahead of its time, thanks to the deftness of Cochran and the dream team's initial leader Robert Shapiro (played by John Travolta), in turning the trial of an almost certainly guilty celebrity into a trial of the LAPD itself.
He is almost certainly not guilty.
Tells about a case Tink takes on for which he must find evidence to defend a man who seems, to the writer, to almost certainly be guilty.
Indeed, so genuinely left-leaning and right-on are Dulwich Hamlet, their players and fans almost certainly felt guilty for spanking their guests 6-0.
For decades, American juries have been instructed that when a person is found in unexplained possession of recently stolen property, it is proper to infer that the person knows it is stolen, and thus almost certainly is guilty of receiving stolen property.
Not only did he suggest that in his conclusions in law essentially his verdict he would almost certainly find Microsoft guilty of maintaining its monopoly by unlawful means.
