I look in the 2008 law book and have found nothing that prohibits it, bit of a novice so hopefully some of our well informed brethren will help out. That I know of there were no changes to the investigation committees setup.EDIT: please look at Brother Bills post in reference to Article 412
I am guessing you are referring to a Petitioners Investigation committee and not a Member in Arrears Investigation Committee. If this is the case here is the section of the law that I found discussing the committee.
Art. 407. Referred to Committee. A petition for the degrees
shall be presented at a stated meeting and referred by the Master
presiding to a committee of three members for investigation and
report. A member of this committee may not be a recommender
or any Mason listed as a reference on such petition, unless and
except no otherwise qualified Brother is available to serve as
such. Such report may be made at a subsequent stated meeting;
but no ballot shall be taken thereon in less than one lunar month
from the date the petition is received, unless dispensation is
granted by the Grand Master under Article 414.
The Lodge may grant the committee further time upon
request of one of its members; but no recommitment may be made
after the committee has reported to the Lodge. (Revised 2008)
Art. 408. No Standing Committee. No standing committee
shall be appointed for investigation of candidates petitioning for
the degrees.
Art. 409. New Committee: When. When the investigating
committee fails to report within two months, it may be
discharged,and a new committee appointed, which shall report
at a subsequent stated meeting.
I hope this helps there are a couple of other places where it talks about the WM appointing a committee and even in those areas I did not find anything that stated the WM could not appoint himself.