LOS ANGELES — Mixed martial arts star Tito Ortiz claims his ex-porn star girlfriend is addicted to Oxycontin, and he blames Jenna Jameson's drug use for his arrest Monday on suspicion of domestic violence.

Ortiz was arrested in Huntington Beach at the home he shares with Jameson and their twin sons. Several hours after posting bail, Ortiz and his attorney accused Jameson of drug addiction and claimed Ortiz never struck her.

"Jenna Jameson has been fighting an ugly battle with an addiction to Oxycontin for well over a year, and this morning, she had a relapse," attorney Chip Matthews said. "We're here because Tito was trying to help her. Tito Ortiz never laid a hand on Jenna."

Ortiz wept openly at the hastily arranged news conference at an Italian restaurant in North Hollywood, saying the support of his family and Jameson's father "just means the world to me."

"My parents have gone through an addiction, and I'm seeing a mirror of that," Ortiz said. "I hold everything dear to my heart that Jenna will be OK."

Ortiz is a former UFC light heavyweight champion whose celebrity has eclipsed his MMA accomplishments since he began a relationship in 2006 with Jameson, perhaps the world's most famous adult film actress. Jameson, who crossed into the mainstream after publishing a popular autobiography in 2004, gave birth to the couple's twin sons, Jesse and Journey, in March 2009.

Matthews said the 35-year-old Ortiz found drugs in their home Monday morning, leading to the confrontation that ended with Ortiz's arrest. Matthews also claimed the 36-year-old Jameson has made 911 calls threatening suicide over the past year, but Ortiz stuck with his partner of four years in hopes of salvaging their relationship.

A call to Jameson's representatives went unanswered late Monday night. Jameson posted one message on her Twitter account Monday, saying she planned to quit Twitter.

"I cant take any more abuse from ANYONE.. To my sweet fans...thank you," the message read.

Jameson and her father, Larry, spoke to TMZ.com and other reporters outside the home earlier Monday. Wearing a wrap on her right elbow, Jameson described herself as "completely shocked" by the incident, saying Ortiz had "lashed out" at her, leaving her feeling "betrayed."

Matthews said Jameson's father initially called 911 after the couple's argument, but provided support to Ortiz after learning of his daughter's drug abuse, even bringing clothes to Ortiz after he made bail. Matthews said a restraining order is keeping Ortiz away from Jameson.

Police Lt. Mike Reynolds said Ortiz was taken to the Huntington Beach jail and released after posting $25,000 bail. Reynolds said police can't make an arrest on suspicion of domestic violence unless there's a "visible injury," and the unnamed victim's injuries met that standard.

Matthews said Jameson has "a scratch on her elbow, and oftentimes when people are on Oxycontin, they don't have the best balance."

Although his career has waned, Ortiz is among the most decorated and popular fighters in MMA history. Ortiz, whose nickname is the Huntington Beach Bad Boy, is a former collegiate wrestler and has been competing in the growing sport since 1997.

He was the UFC's light heavyweight champion from 2000 to 2003 during the formative years of the sport's dominant promotion, making five title defenses before losing his belt to Randy Couture. After his career declined amid several injury problems, including major back surgery, Ortiz left the UFC in 2008 in a bitter dispute with president Dana White, his former manager.

Ortiz re-signed with the UFC last year, losing a split decision to Forrest Griffin in his return fight last November. Despite his celebrity and business ventures, including a clothing line, Ortiz is winless in his last four UFC fights since October 2006.

Ortiz served as a coach on the most recent season of "The Ultimate Fighter," the UFC's popular reality television show currently airing on Spike. Yet he apparently was forced to drop out of the show during its taping earlier this year, and the UFC already has announced it will replace him with Rich Franklin for the show's traditional season-ending bout with fellow coach Chuck Liddell.