Two suspects accused of killing a Texas teen while she was on vacation in Milwaukie, Ore. were arraigned on charges of murder, attempted rape and sex abuse Tuesday, authorities said.

 VIDEO: Watch KGW report on latest charges

A Clackamas County grand jury added the attempted rape and sex abuse charges against Alejandro Rivera Gamboa and his cousin, 23-year-old Gilberto Javier Rivera Gamboa.

If convicted, both men could face the death penalty.

The Gamboas admitted they came to the United States illegally.

Police said 15-year-old Dani Countryman was trying to fight off the cousins when they strangled her at a Milwaukie apartment in late July.

Alejandro was taken into custody last Saturday on an outstanding warrant for an unrelated probation violation involving drunk driving. The murder charges were later added.

Gilberto Javier Rivera Gamboa was arrested the previous Monday on aggravated murder charges at the Balboa apartment complex where he lives just a few doors from where Countryman was discovered.

The two also faced an immigration hearing after the murder investigation was complete. According to immigration officials, both of the suspects admitted to entering the country illegally six months ago.
Court records showed Alejandro admitted to stepping on the girl and holding her down and that the two tried to sexually assault her.

More: Countryman surprised her attackers by fighting back

"She was only 5 foot and 95 pounds," said 20-year-old Ashley Countryman, the half-sister who found Dani's body the morning after a going-away party. "I don't think they were expecting such a fight out of her."

Ashley said she can't get the image of her half-sister's lifeless body out of her head.

"I mean it was just a harmless night that went terribly, terribly wrong," she said.

Ashley thinks there was only a small window of opportunity for the attack. She said she last spoke with her half sister about 5 a.m. that day. Three hours later, she found Dani dead.

"They had to have been planning this, at least had the idea in their head... it's just random... I mean, this is the first time they'd ever met her," she said.

According to Ashley, the two men had been outside an adjacent apartment and at one point gave Dani a beer. They were vulgar toward other women, witnesses said, but never got physical with Dani, at least not from what Ashely could see.

"You know, I remember them flirting with her, but it wasn't a big thing, you know," Ashley Countryman said.

Also: Timeline

Clackamas County investigators said Countryman scratched the men who killed her, providing valuable DNA evidence under her fingernails that led to two arrests, according to the Dallas Morning News.

Forensic scientists from Oregon State Police said a shoe seized from one of the suspects, Alejandro, 24, had blood on it. The pattern of the shoe was also consistent with the imprint on Countryman's chest, according to investigators.

"They've taken her life, why should they be alive?" Countryman's great-uncle Carl Barton said. "I have no sympathy for people like that."

On July 27, the sisters attended a party at an apartment complex in the Portland suburb of Milwaukie. Then, they spent the night in separate apartments, and Ashley found Dani's body under a blanket when she went to get her in the morning.

KGW graphic

Ashley Countryman said other guests were sleeping in the room where she found Dani. And the couple who lived there with their two toddlers were asleep elsewhere in the apartment.

Countryman, from Kaufman, Texas, was from a troubled home and struggled with drugs, according to family members.

More: Victim was having rough year with father in jail

"It is very satisfying for the sheriff's office to announce the arrest of these murder suspects, which will hopefully bring a modicum of relief to the community, the victim's family and friends," said Detective Jim Strovink, a spokesman for the sheriff's office.

Some neighbors described the apartment building as a trouble spot.

Background: 55 police calls to apartment complex

If the case goes to trial, there's no guarantee they'll be deported after that. Officials said the criminal process takes precedence.

(AP and the Dallas Morning News also contributed to this article.)