Solution:

At every floor, the detective had to open the window himself. If the man had committed suicide, then at least one of the windows must have been open. A person who is committing suicide won’t close the window behind him. Thus he knows that someone pushed him off the edge and closed the window afterwards.

Solution:

If the man killed himself, he would not have been able to rewind the cassette. Thus it is clear someone else killed him.

Solution:

It is possible that the man was a deep sea diver. Such divers must wear a pressurized suit to withstand the pressure in the depths of the sea. If it tears down accidentally, the person will die. But for a short period of time, the breathing apparatus can keep him alive.

Solution:

Kid1, he was left with one rock.

Solution:

The person is leaving hospital after visiting his wife. His wife is on a life support system. The elevator has stopped due to the power cut. If there was an emergency backup generator functioning well, the elevator would have also be running. It stopped in between means that the life system support has stopped as well.

Solution:

Dabid is the killer

drawing room(D) , art room(a) , bed room (b) , ice-cream room (i) , desk room (d)

Solution:

Newspaper delivery man was the murderer because of absence of Wednesday and Thursday missing newspaper.
This indicates he already know that there is no one to read it.

Solution:

Jeff Killed Mike

1. Jack is not the murderer, because he is the brother of the murderer.
2. Dan can't be the murderer since he ran a marathon, and the murderer recently had his leg amputated, and wouldn't be running a marathon of any magnitude that quickly.
3. Ben is not the murderer if he just met Jack, since Jack and the murderer grew up together.
4. This leaves Jeff and Mike.

Since Jeff is still alive (he wants to install a new computer next week, present tense) he must be the murderer. Mike also didn't grow up with Jack. It has been determined that Jack, Dan and Jeff are all alive. Ben must also be alive since Jeff plans to install Ben's computer next week. This means that Jeff killed Mike.

Solution:

A parachute that didn't open.

Solution:

The doors at 'The Coconut Grove' opened inward. In the mad panic to escape the fire, people were crushed against the doors and could not pull them open. After 'The Coconut Grove' disaster in 1942, all public buildings had to have doors which opened outward.