By Ellen Wulfhorst

FORT HOOD, Texas (Reuters) - U.S. Army Major Nidal Hasan, facing the possibility of a death sentence for the November 2009 shooting rampage at Fort Hood, Texas, rested his case without making a statement in the sentencing phase of his trial on Tuesday.

The jury of 13 military officers, who convicted the Army psychiatrist of killing 13 people and wounding 31 others, was instructed to return to court on Wednesday, when it will likely begin deliberating Hasan's sentence. Most of those killed and wounded were unarmed soldiers.

Given the opportunity to address the jury before the deliberations begin, Hasan declined to make any statement nor present any evidence in his defence.

"The defence rests," said Hasan, who has acted as his own attorney.

The most he has said in court was in his opening statement on August 6, when he admitted to being the gunman at the central Texas Army base and said he had switched sides in what he considered to be a U.S. war on Islam.

Standby defence attorneys for Hasan attempted to present so-called mitigating evidence that could be used to argue for a life sentence rather than the death penalty. That included details on his background, family life, education, military experience and logs of his behaviour in jail.

"If no one makes a case for life, there is only death," said Lt. Col. Kris Poppe, one of the attorneys assigned to Hasan's case.

But Hasan objected to the effort on his behalf, telling Judge Colonel Tara Osborn he had "overzealous defence counsel."

The judge ruled in Hasan's favour, saying he should be allowed to control his side of the case.

"Major Hasan is the captain of his own ship," the judge said after repeatedly reminding Hasan that he could mount a stronger defence of his life.

"It is my free and voluntary decision," he told the judge at one point.

An American-born Muslim, Hasan earlier told mental health evaluators he wanted to become a martyr, and lawyers assisting him have said he was actively seeking the death penalty.

Hasan, 42, has disputed that claim.

The discussions about Hasan making little or no effort to argue for his life took place without the jury present.

Seated in a wheelchair, Hasan was bearded and wearing a camouflage Army uniform. He frequently rubbed his forehead and spent much of his time thumbing through court papers on the table in front of him.

He uses the wheelchair after being paralyzed when shot by police to end the rampage at the U.S. Army base, just weeks before he was to be deployed to Afghanistan.

The military jury convicted him on Friday of 45 counts of premeditated murder and attempted premeditated murder in what was the deadliest mass murder ever at a U.S. military base. The same jury can now sentence him to death or to life in prison.

Twenty family members and victims gave evidence during the prosecution's side of the sentencing phase. The prosecution concluded its case earlier on Tuesday.

Joleen Cahill, testified that she and her three children have struggled with emotional, health and work issues since the death of her husband, retired Chief Warrant Officer Michael Cahill, 62, an employee at Fort Hood. The couple had been married for 37 years.

One night, the widow said, she found herself having a thought that she described as one "you shouldn't have," without elaborating, and realized: "I need to start fighting back."

"The shooting is not going to destroy my life or my children's. He is not going to win. I am in control," she said.

If the jury unanimously recommends death as his punishment, Hasan could face lethal injection, possibly making him the first U.S. soldier to be executed by the U.S. military since 1961.

A death sentence would mean the start of a lengthy process requiring the approval of the Fort Hood commanding general, and the U.S. president, in order for there to be an execution.

(Additional reporting by Jana J. Pruet; Editing by Paul Thomasch, Matthew Lewis and Bob Burgdorfer and Gunna Dickson)