In case you don't know, "2nd BN" is 2nd Battalion. "1st Marines" is 1st Marine Regiment. The 1st Marines were one of the infantry regiments in the 1st Division. You can try to get his service record. Info on how to do so can be found at this address: http://www.archives.gov/facilities/mo/st_louis/military_personnel_records.htmlhttp://www.archives.gov/facilities/mo/st_louis/military_personnel_records.html
You can try to get his Individual Deceased Personnel File. Write to this address (including all pertinent info such as name, unit, etc) and be sure to cite the Freedom of Information Act in your request:
US Total Army Personnel Command Attn: TAPC-PAO (FOIA) 200 Stovall Street Alexandria, VA 22332-0404
(I know this says Army, but they also hold Marine Corps records for this period.)
I have also seen the following info posted online. I don't know if it is accurate.
"When a Marine dies, a Report of Casualty (DD1300) is issued by the military; in addition, a death certificate is issued by the State in which the death occurred. (When overseas, the death certificate is filed in the state of residency.) A Marine Corps officer notifies the next of kin in person. Upon written request, the next of kin can request all the paperwork filed by the United States Marine Corps in the course of the death investigation (all deaths are investigated as a routine procedure). As part of the investigation, the death certificate is requested by the investigating officer from the state and filed with the Marines Official Records. The references pertaining to this are 10 USC Section 2271, DODI 1300.9, and MCO P1741.8.
Copies of Marine Corps death certificates may be obtained from: Marine Corps Commandant Code M-HP-10 Headquarters Marine Corps 2 Navy Annex Washington DC 20380-1775 Phone 703-696-1177 Fax 703-696-2072"
Getting info at these sources would no doubt be facilitated if you could include his serial number. For a marine it would be a six digit number. It might be included on his gravestone, in correspondence from the Corps, or War Dept, etc.
As a very long shot in finiding someone who knew him, you might also try contacting the division vet assn. They have a website, with message board (headed "GuestBook") at this address: http://www.1stmarinedivisionassociation.org/http://www.1stmarinedivisionassociation.org/