ORINDA, Calif. -- Police announced this week that there is no evidence of a crime in the death of a 16-year-old boy at a party in Orinda in May.

Joseph Loudon died May 23 after choking on his own vomit after drinking alcohol and ingesting a pharmaceutical drug at a large party at a home in the 100 block of Hillcrest Drive, according to Orinda police.

Paramedics found Loudon unresponsive in the home and took him to Kaiser Permanente Walnut Creek Medical Center, where he was pronounced dead.

Toxicology tests found alcohol and the pharmaceutical drug papaverine in Loudon's system, although his blood-alcohol level was low. Detectives tried to trace where the drug came from but were told there was not enough probable cause to secure a search warrant, police said.

"After three months of interviews and investigating, there is no evidence of a crime, nor is their any indication that Loudon's death was accidental," Orinda police Chief Bill French said in a prepared statement.

"There is nothing to indicate that a hazing was taking place or that Loudon was forced to consume any alcohol or drugs," French said.

The last time a prescription was filled for that drug in local pharmacies was more than three years ago, and there had been no reports of any theft of medications in Orinda, according to police.

"Our greatest frustration is that there are individuals who may have knowledge about the circumstances surrounding the papaverine, yet no one is talking," French said.

Police have arrested 18-year-old Patrick Gabriella on suspicion of contributing to the delinquency of a minor and furnishing alcohol to a person under 21 years old.

They announced this week that similar charges will be sought against his sister, Alexandra Gabrielli, 19. A 16-year-old boy was also arrested for allegedly furnishing alcohol to a minor.

During the investigation, police discovered that several students at Miramonte High School, which Loudon attended, had fake ID cards.

Investigators were told that 22-year-old Rohnert Park resident Robert Martin Scott had provided the teenagers with the forged driver's licenses.

When investigators went to arrest Scott, they allegedly found about 100 fake licenses in his home, police said.

Scott was arrested for forgery and identity theft, and has also been federally indicted for manufacturing and distributing counterfeit government identification cards, according to police.

Anyone with information on the case is encouraged to contact the Orinda Police Department at (925) 284-5010.