Lets deduce then shall we?
A hand is clearly leaning against the window. Now we know people have been in Sherlock’s home, but they left no finger prints since the only way for Sherlock to find out where they had been was via dust. So it had to be someone who is welcome in the apartment.
If you look at how high the hand is, they are tall. So that clearly rules out John and Mrs Hudson.
Now if you will, notice the smudge marks in a circle just under it. About the size of a head. But if you look at the hand its flat on the glass meaning the person who made it had to have been facing the window, the other smudge was made by someone who was facing the other way…
Now who is tall with big hands that is often in the apartment?
Not a big stretch to establish that is Sherlock’s hand print.
Here is where it gets juicy…
The head smudge is just taller then John.
SO in conclusion.
I put forward, John was lifted by Sherlock, back and head to the window, while Sherlock had his hand on the window for support….
Thank you. Good day sir.