The hanging tree

The Hanging Tree illustration from The Mocking Jay, The Hunger Games book by Suzanne Collins

Lyrics:

Are you, are you

Coming to the tree
Where they strung up a man they say murdered three?
Strange things did happen here
No stranger would it seem
If we met up at midnight in the hanging tree.

Are you, are you
Coming to the tree
Where the dead man called out for his love to flee?
Strange things did happen here
No stranger would it seem
If we met up at midnight in the hanging tree.

Are you, are you
Coming to the tree
Where I told you to run, so we'd both be free?
Strange things did happen here
No stranger would it seem
If we met up at midnight in the hanging tree.

Are you, are you
Coming to the tree
Wear a necklace of rope, side by side with me...
Strange things did happen here
No stranger would it seem
If we met up at midnight in the hanging tree.

Meaning:

You realize the singer of the song is the dead murderer.
He's still in the hanging tree.

And even though he told his lover to flee, he keeps asking if she's coming to meet him.

The phrase Where I told you to run, so we'd both be free is the most troubling because at first you think he's talking about when he told her to flee, presumably to safety.

But then you wonder if he meant for her to run to him. To death.

In the final stanza, it's clear that that's what he's waiting for.
His lover, with her rope necklace, hanging dead next to him in the tree.

I used to think the murderer was the creepiest guy imaginable.
Now, I decide not to judge him without knowing more details.

Maybe his lover was already sentenced to death and he was trying to make it easier. To let her know he'd be waiting.

Or maybe he thought the place he was leaving her was really worse than death.