a)There must be some bleeding under the skin or wounds formed by scratch by glass or scratch by the victim on the surface of the suspect's body.We might be able to find one of the suspect's cloth with bloodstain,and the blood was from the victim.And if he weared a trousers during that day,some coffee stain may also could be found at the bottom of the trouserrs or shoes.
b)Both at the inside or outside lateral door handle have the possibility of finding the fresh fingerprinting from the suspect or the victim.
c)The bloodstain on the wall didn't have too much velocity when they reached the wall.The ashtray in the sense might be the weapon that the suspector used,if there was some bloodstain .Or something blunt and easy to brandish,and was taken away by the suspector.If the weapon was taken away,it may could be found from the house that the suspect is living,or the transport that the suspect has used.
d)Witness 3's report may be fake.The disturbance was heart at 10 p.m,so it's hard to appear in Jurong Point at 10:20 p.m after disturbance.
e)
f)May be the younger son of the landlords.