McALLEN - An overdose of a powerful animal tranquilizer caused the death of an Oregon woman found dead earlier this week in a Nuevo Progreso hotel room, Mexican police officials said Wednesday.

The results of an autopsy conducted on 32-year-old Jennifer Malone bolstered claims made by a man who told U.S. authorities he helped her to commit suicide.

But in the eyes of Malone's boyfriend, what Jeff Ostfeld did to the once successful real estate agent was nothing short of murder.

"If there weren't guys like this Jeffrey out there, I have no doubt that Jenny would still be alive," said Thomas Piazza, who lived with Malone in Roseburg, Ore.

U.S. customs agents arrested Ostfeld, 33, of Las Vegas, on Monday at the Progreso-Nuevo Progreso International Bridge, moments after Tamaulipas State Police found Malone's body in a room at Las Flores Inn in Nuevo Progreso, on the Mexican city's bustling tourist strip.

When questioned about the 1,200 milliliters of barbiturates found in his possession, he told agents he had purchased the drugs in Mexico to help others like Malone end their lives.

Piazza had no doubt when contacted by phone Wednesday that his girlfriend willingly met with Ostfeld in Mexico but said he had struggled for months to help treat his girlfriend's chronic depression.

"Jenny was loved by a lot of people up here," he said. "We are just devastated. We thought we had her under control."

Malone's mental state had rapidly deteriorated after the collapse of the West Coast housing market prompted a move to Florida, Piazza said.

She had tried to take her life on previous occasions and had been caught researching euthanasia on the Internet as recently as last week. But despite her mental struggles, she remained in excellent physical health.

"If she had been 80 years old with a brain tumor, then something like this might make sense," Piazza said. "She was 32, beautiful and perfectly healthy."

While Piazza had never heard of Ostfeld before this week, he suspects Malone may have received a call from him days before she disappeared from Oregon on Friday.

Mexican investigators believe that after flying into McAllen, both she and Ostfeld checked into the hotel room in which she was later found. They are still trying to corroborate that story, however, with the Las Vegas man, who remains in U.S. custody.

Ostfeld is scheduled to appear before a U.S. magistrate judge Friday on federal drug smuggling charges.