No motive is necessary to murder Altantuya?

Look at the following pictures and tell me, who in his right mind would want to murder her and then blow her to smithereens, unless the perpetrator is prompted by some very strong motives to do what he did.

Yes, the lady above is none other than Altantuya Shaariibuu who was shot twice in the face and then blown up to bits and pieces by C4 explosives.

However, this judge said motive was not a necessary element in the case and therefore found it necessary to acquit Abdul Razak Baginda.  Now I am trying to understand the rationale here.  If a person can do things without a motive, then the person must have taken leave of his senses, or his mental faculty.  As such the person would be ruled as being not of sound mind, which will lead to acquittal on grounds of insanity.  However, to prove that the person was insane, the accused must have gone through a series of psychiatric tests.  I doubt the acquittal was based on such a premise, which in any case Razak did not look insane to me, from the photos I have seen.  How did our learned judge come by with this conclusion?