Bonjour,
Réponse :
a) The man killed Ms Donovan. He used a knife
The man who killed Ms Donovan used a knife.
.b) It was 9:00 pm. The crime occured.
It was 9:00 pm when the crime occured.
c) The forest was the place. We found a body.
The forest was the place where we found a body.
d) He found a hair on the crime scene. The hair was blond.
He found a hair on the crime scene which was blond.
e) The shoes were spotted with blood. The shoes belonged to Mr Donovan.
The shoes which / that were spotted with blood belonged to Mr Donovan.
;)