Yes, my last statement in that paragraph was carelessly worded. I should have said:
Someone or some people may have a vague plan to kill someone or some people in the future, but unless the plan becomes specific and actionable, they haven't committed a crime.
Recently, actions like DUI have been designated crimes, for the purpose of public safety. But still, the law always has to adhere to the long-standing principal that there is a clear line between crime and not-crime, and crossing that line is a deliberate physical action. That someone got into the car and drove while intoxicated over a certain specified limit can easily be proven or disproven. Whether they were or were not alert or driving carefully, etc, is a quagmire of opinions where no truth will ever emerge.
Similarly, to prove M1 against MS in this case, I believe you have to prove there was an action taken in the form of a conversation, along the lines of "Mark, I want you to help me murder someone will you do this?". "Yes, I'm in, tell me what I should do". In that conversation, both people would have crossed a line into the area of criminal offense, and both people would know it.
IMO, that MS was texting about getting food, and DM stating 'I'm on a mission", very much undermines any theory about them being in on a plan.
Again, the point I'm making is that a conviction can't be based on a vague sense someone was up to no good, a right ******, etc. There must be proof of a specific offence, which is a "guilty act" as defined in the criminal code