The Army said today that it was ''probable'' that Sgt. Asan Akbar, a member of a mine-clearing battalion, threw the grenades into officers' tents in Kuwait early Sunday.
The attack killed one and wounded 15 at the scene, but one of the injured, Maj. Gregory Stone of the Air Force, who was based in Boise, Idaho, died today in Kuwait.
Sergeant Akbar will be sent to Mannheim, Germany, to be held for pretrial investigation, the Army said in a statement from Fort Campbell, home of the 101st Airborne Division, now based in Kuwait. The other officer killed was Capt. Christopher Scott Seifert, 27.
The statement said a military magistrate at Camp Virginia, Kuwait, found that ''it is probable that the accused soldier committed the crime and that lesser forms of restraint are either not available or would not be sufficient.''
Sergeant Akbar, 36, also known as Hasan Akbar or Mark Fidel Kools, was not specifically named, but officials have said that he is the only suspect. In Mannheim, the Army said, he faces ''preferral of charges and the conduct of a pretrial investigation'' under the Uniform Code of Military Justice.
In earlier statements, a Fort Campbell spokesman, George Heath, said that Sergeant Akbar, a member of the 326th Engineer Battalion that was deployed to Kuwait with the 101st in late February, had an ''attitude problem'' and that he might have sought retribution for grievances.
F.B.I. agents have been questioning people who knew Sergeant Akbar in the cities where he grew up -- Los Angeles; Baton Rouge, La.; and Clarksville, Tenn. -- and at a mosque in Los Angeles where Mr. Akbar, a Muslim, studied.
F.B.I. agents visited a home in Los Angeles where either Sergeant Akbar or a relative was thought to have lived, but Army investigators continue to take the lead in the investigation, with the F.B.I. assisting.
If evidence points to a terrorist motive, the F.B.I. would most likely open a full investigation, officials said. But ''at this point,'' a law enforcement official in Los Angeles said, ''I don't think there's anything that's pointing to that as the motive.''
Some cite racism as an issue. ''Three years ago, Hasan started complaining about the problems he was having as a black man in the military,'' William Bilal, 52, who is Sergeant Akbar's former stepfather, said today.
Mr. Bilal, who said he was still close to Sergeant Akbar and his mother, Quran Bilal, whom he divorced 15 years ago, added: ''Intermittently over the past few years, he just spoke generally about the same problems, but nothing specific. When this all started he was fresh and just out of college and wanted to do good with his life. The pressure just built on him.''
Mr. Bilal said racism in the armed forces had been a problem for others in the family, including himself. During his Army service in the 1960's ''we saw it all in training and everywhere else,'' he said.
Sergeant Akbar's brother, Ishmael Mustafa Bilal, 20, was honorably discharged from the Air Force recently. The brother said he also experienced racism in the service.
People who knew Sergeant Akbar from his childhood in Los Angeles and in the small Clarksville housing complex near Fort Campbell where he lived in the year before leaving for Kuwait, describe a thoughtful, unexcitable, bookish man who was cordial enough to wave hello but rarely stopped to chat.
In Los Angeles, where Sergeant Akbar spent much of his youth, the imam at the Bilal Islamic Center, Abdul Karim Hasan, 70, recalled an intense and gifted student. Mr. Hasan, who has not seen Sergeant Akbar since his student days, knew him as Mark Fidel Kools.
As a youth, ''he was always deep in thought,'' Mr. Hasan said. ''He was quiet. He was withdrawn. He was not athletic. He was not an outgoing person. He never got involved in any of the potato sack races we'd have here or the basketball games. He was always just reading a book.''
In 1988 he enrolled at the University of California at Davis under the name Mark Fidel Kools, Lisa Lapin, a spokeswoman there said, and graduated nine years later using the name Hasan Karim Akbar. Ms. Lapin said she did not know when his name changed. She said he graduated with degrees in aeronautical engineering and mechanical engineering.
In Clarksville, he lived in Bancroft Circle, a placid, racially mixed neighborhood of eight motellike, one-story brick structures, each with four two-bedroom apartments, surrounding an open grassy circle with a ditch through the center. The only thing differentiating the structures is the color of their shutters. The rent is $450 a month.
Sergeant Akbar lived in the building on the far side of the circle with blue shutters. Willie Shamell Jr., 39, the neighbor who said he knew him best, said some neighbors called Sergeant Akbar Speedy because he drove his red pickup truck over speed bumps without slowing.
Mr. Shamell said he never saw anyone visiting him. ''Girlfriends, male friends, no one,'' he said.
Other neighbors were also struck by his solitude and the lights that burned in his home late into the night.
''He was always alone,'' Trill Brown, 19, said.
Mike Oliver, who lives across the circle from Sergeant Akbar's home, said: ''If you're in the Army at Fort Campbell, somebody is going to visit you. But nobody visited him.''
Lester Johnson, another neighbor, said, ''He wasn't a guy who'd say, 'Hey, what's up?' ''
Sometimes, Mr. Brown said, Sergeant Akbar would slow down to wave to the teenagers and young children playing basketball on the edge of the circle.
In its statement today, the 101st described in new detail the events of 1:21 a.m. on Sunday while members of the division's First Brigade ''were either preparing for bed or already asleep.'' It said, ''A series of three explosions rocked three tents near the brigade headquarters.''
''It appears that the explosions were the result of three grenades that were thrown or rolled through the front door of each of these three tents,'' it said. ''The grenades were both fragmentary and incendiary devices designed to cause either death or other serious battlefield injuries.
''Shortly after the explosions, a soldier was taken into custody as a primary suspect in this event. There were a number of reasons why members of his command suspected him of being involved in this crime. However, he was treated fairly and received the advice of a military defense counsel as quickly as one could be made available.''
Mr. Bilal, an air-conditioner repairman, said government investigators had not approached him or Sergeant Akbar's mother. He said she was in hiding. ''She doesn't want to have anything to do with this,'' he said.