Police are investigating after a woman fell from a window in the Whittington Moor area of Chesterfield.
At 10.20pm on September 30, officers received reports that a woman had been seen to fall from the first floor window of a flat in Station Road.
The 45-year-old woman was taken to hospital with serious injuries and is now recovering at home.
A Derbyshire Constabulary spokesperson said: "Her fall was witnessed by a man who detectives are now trying to trace as a matter of urgency.
"The man was young, white and walking with a black Lurcher type dog.
"Officers have arrested a 46-year-old man, from Chesterfield, on suspicion of grievous bodily harm and has been bailed.
"Anyone who thinks they may know who the witness described above is asked to contact Derbyshire police on 101, quoting reference 19*522705."