Michael Kahnwald leaves behind a suicide note after he hanged himself from a beam in his attic studio at the Kahnwald family home on June 21, 2019. It is initially unclear why he commits suicide. The envelope reads "Do not open before November 4, 10:13 P.M."
There seems to be a rift between Ines Kahnwald and Hannah Kahnwald over what happened as there is a Christmas photo of the Kahnwald family with Ines ripped out in Hannah's bedroom. Ines has a similar photo with her intact. Also, Hannah leaves a voicemail for Ines:
"It's Hannah here. The power's out again. I mean, if you want us out of the house, then just say so. Your grandson hasn't seen you in over three months. Do you think Michael wanted that? That's sick. You're sick."
Ines Kahnwald has possession of the letter after the suicide. She broods over it in her apartment, perhaps to the detriment of everything else, awaiting the described time and finally opens it and reads it.
Dark Season 1 Episode 1: "Secrets"
The Stranger leaves a package with Regina Tiedemann at Waldhotel Winden to deliver to Jonas Kahnwald the evening of November 7, 2019. The package includes Michael's suicide note (that looks very old/aged), along with the futuristic lamp and geiger counter. The suicide note reads:
"Dear Jonas, By the time you read this everything will have happened, irrecoverably. It can no longer be changed.I would have liked to explain things to you sooner, but I hope once you understand how everything is connected, you will understand my decision. The truth is a strange thing. You can try to suppress it, but it will always find its way back to the surface. We make a lie into our truth in order to survive. We try to forget. Until we can't anymore. We don't know even half of the mysteries of this world. We are wanderers in the darkness. This is my truth. On November 4, 2019 I traveled through time to the year 1986. They boy from the future stayed. And in time he became a man. Mikkel became Michael, who never knew where he belonged. By the time you read this I'll already be gone. Both as a boy and as a man. I hope you can forgive me. Everything is connected. Mikkel / Michael"
Dark Season 1 Episode 5: "Truths"
Jonas Kahnwald burns the suicide note on November 9, 2019 after deciding not to tell Hannah what he has discovered. Perhaps, believing he cannot change what has happened to Mikkel/Michael nor his own fate.
Dark Season 1 Episode 7: "Crossroads"
On November 12, 2019, Jonas Kahnwald confronts Ines Kahnwald (his adoptive grandmother) to see if she knew about Mikkel's origins. She ends up giving him the suicide note, which appears to only be a few weeks old. He thinks it impossible since he just burned it a few days ago.
Dark Season 1 Episode 10: "Alpha and Omega"
Complete Timeline of the Suicide Note
The suicide note is created by Mikkel/Michael based on the letter that Jonas shows him in 2019. It is left on the counter in his workshop when he commits suicide, and Ines picks it up before anyone in the family can see it. Ines keeps it until the "open by" date on the front of the envelope (five months later, in November), at which point she opens and reads the letter.
About a week after she opens the letter, a young Jonas confronts her about what she knows about Mikkel being Michael. She shows Jonas the suicide note, to which he comments, "I burned this." He reads the letter and holds on to it.
Jonas goes through getting abducted by Noah, portaled to the future, God machined back to 1921, then dropped onto the day before his dad kills himself. He shows him the suicide note. Michael reads the note, which tells him what he needs to write in it. He then "creates" the note, and kicks off the whole thing again.
Jonas has to then hold on to this letter for another 33 years. At which point, he'll travel back to 2019 and have Regina deliver the note to the young Jonas, so he can read it and burn it, just before going to Ines and getting the 5 month old version of the letter, thus completing the loop.