(Updates with suspect dead, details; in paragraphs 1-5)
By Barbara Liston
ORLANDO, Fla., May 27 (Reuters) - A U.S. military veteran suspected in the Memorial Day weekend killings of three people in Florida died on Tuesday after he shot himself during a standoff with a SWAT team in Tennessee, officials said.
David Smith, 27, who was described as delusional, is believed to have killed the three victims, one of whom was his sister, sometime between Saturday and Monday in Lakeland, Florida, law enforcement officials said.
On Tuesday, Smith called authorities in Tennessee and said he was wanted for murder in Florida and was holed up at a motel in West Knoxville.
Smith fired multiple shots from his motel room during negotiations for his surrender but eventually became quiet, according to a statement from the Knox County Sheriff's Department.
Agents gassed and then stormed his room where they found him injured from a self-inflicted gunshot wound. He was pronounced dead after he was taken to a local hospital.
Smith was located after an overnight manhunt, said Sheriff Grady Judd of Polk County, Florida.
He said Smith was a U.S. Army veteran with the 82nd Airborne Division who had served in Iraq and Afghanistan.
The bodies were discovered by Smith's 14-year-old niece who had been away for the weekend on an ROTC trip and found her mother - Smith's sister - and two others dead when she returned. Smith also had recently lived in the home.
"It was a very violent scene," Judd said.
He identified two of the dead as Danyala Smith, 31, sister of the suspected shooter, and Nikosi Williams, 25, a visitor at the house. The third victim has not yet been identified.
The sheriff said Smith had left the military several years ago and suffered from post-traumatic stress disorder. He described Smith as a paranoid loner.
Smith had previously been hospitalized involuntarily for his mental condition, and was posting delusional statements on Facebook, Judd said.
"I don't know who could have done more, but I know a lot of people in the family tried to help him," he said. (Editing by David Adams, Matthew Lewis, Kevin Gray and Mohammad Zargham)