WASHINGTON (AP — Thejmittee headed by Hep. F. Ed4 alleged massacre of Vietnamese warn Hebert, D-La. civilians at My Lai was deliber-1 Other PtMtiagsately covered up under an agreement by military and State Department officers in the field, a special House subcommittee has charged.Reports of atrocities by U.S. soldiers promptly spread through 13 different command levels in the Americal Division, support units and U.S. adviser groups, the subcommittee said in a report released Tuesday. But there is no evidence they ever reached headquarters in Saigon, the report added.Evidence SuppressedThe subcommittee believes the explanation lies in a concerted action among military and State Department officers to suppress all evidence of the allegation and its investigation, the report said.... The subcommittee. the report said, was unable to determine when, and by whom, that decision was made, and consequently is unable to describe the scope of the agreement.The report, based on still-secret testimony by 132 witnesses, was released by a special house appointed investigating subcom-Other principal findings of the investigation into the Task Force Barker sweep against the suspected Viet Cong stronghold at My Lai March 16. 1968:—Heticopter Pilot Hugh C. Thompson testified that when he landed to rescue Vietnamese civilians from a, bunker, a lieutenant in charge of GIs standing over bodies in a ditch told him.The only way I could get them out is with s hand grenade* or something of that order. But Thompson denied having helicopter guns trained on GIs during the rescue.—Acts by individual GIs were so wrong and uncharacteristic si to immediately raise a question as to the legal sanity at the time of those men involved.Waste Cede Revised —The Uniform Code of Military Justice should be revised to prohibit court-martial for such acts m combat until the accused man's mental responsibility at the time has been determined.—The sole written record of s held investigation — concluding only 20 Vietnamese civilians were killed in artillery, heticop-