Jun Dumaguing, Associated Press
U.S. Marine Pfc. Joseph Scott Pemberton, third left, the suspect in the Oct.11, 2014 killing of Filipino transgender Jennifer Laude at the former U.S. naval base of Subic, northwest of Manila, is escorted into the courtroom for his scheduled trial Monday, March 23, 2015 at Olongapo city, Zambales province, northwest of Manila, Philippines. Pemberton was tagged as the suspect in the killing which the protesters termed as a "hate crime" against LGBT (Lesbian, Gay, Bisexual and Transgender) Filipinos.

MANILA, Philippines — A Philippine court on Wednesday began the trial of a U.S. Marine charged with murdering a transgender Filipino after allegedly discovering her gender when they checked into a hotel in an emotional case that has tested America's ties with a key Asian ally.

U.S. security escorts brought Marine Pfc. Joseph Scott Pemberton, who was wearing handcuffs and a dark business suit, into a heavily secured court room in Olongapo city, northwest of Manila, for the trial after a plea bargain negotiation with the family of the victim, Jennifer Laude, reportedly collapsed, lawyers for Laude's family said.

Government prosecutors expressed confidence they could convict him this year.

"We will prove the elements of murder," state prosecutor Emilie de los Santos told reporters, referring to what she has described as "treachery, abuse of superior strength and cruelty" that aggravated the attack against the victim, who was formerly known as Jeffrey Laude.

The anti-tank missile operator from Bristol, Massachusetts, allegedly strangled Laude and then drowned her in a hotel toilet in October last year after discovering she was a transgender woman. They had checked into the hotel after meeting in a red-light district disco bar, according to Filipino state prosecutors.

Pemberton was bar-hopping with fellow Marines at the time after participating in joint U.S.-Philippine military exercises.

Government prosecutors presented their first witness, hotel worker Elias Gallamos, who identified Pemberton as the man who was last seen with Laude shortly before she was found dead on Oct. 11. Gallamos pointed to Pemberton, who sat in the courtroom crowd, according to Ethel Avisado, a lawyer for Laude's family.

"Above anything else, we want to give justice to Jennifer," Avisado told The Associated Press by telephone from Olongapo. "And we want to be sure that there will no longer be other Jennifers in the future," she said, adding that the government needed to gain better control over visiting military forces in the country.

The case reignited a debate over custody of American military personnel accused of crimes. But the looming irritant between the treaty allies over Pemberton's custody was eased after Washington agreed to move him from a U.S. warship shortly after the killing to the Philippine military's main camp in metropolitan Manila, where he remains under American custody with an outer ring of Filipino guards.

Weeks before the trial, talks spread that both sides have begun quietly discussing a possible plea bargain agreement where Pemberton would reportedly plead guilty on a lower charge in exchange for money for the Laude family. Both sides on Monday denied initiating the talks.

Laude's mother, Julita, told reporters she would not drop the case against Pemberton even if she was offered a million dollars.

"What they did to my child was gruesome," she said. "Just because we are poor doesn't mean we can't fight for justice."

The touchy case occurred at a time when the Philippines and the United States have strengthened ties with the recent signing of a defense accord that allows greater U.S. access to Philippine military camps. The accord will help Washington's bid to reassert its presence in Asia, and enable Manila to deter what it calls China's aggressive moves to reinforce its claims in disputed South China Sea territories.