SAN JOSE — An experienced corporate chemist and pharmacist from South San Jose became an accused would-be killer on Monday in bizarre fashion: By eschewing her vast expertise and allegedly making a crude mix of rubbing alcohol and orange juice that police say she tried to sneak into the display case of a Starbucks just as it was filling with high-schoolers.

Police haven’t revealed whom, if anyone, might have been targeted. But they felt strongly enough to arrest Ramineh Behbehanian on suspicion of attempted murder after the ploy was literally sniffed out by an alert customer and a sharp-eyed employee who took note of her car’s license plate number as she made a hasty exit.

Initial tests of the bottles revealed them to have a potentially lethal amount of the household solvent.

“If it weren’t for the actions of that customer, I believe we’d be talking about a homicide right now,” said Sgt. Jason Dwyer, a police spokesman.

Behbehanian, 50, has been in jail without bail since her Monday night arrest. Police say it remains unclear why she allegedly put the tainted juice bottles into the refrigerated display case at the coffee chain’s shop on Snell Avenue.

Luckily, no one drank the toxic concoction, largely because the alleged means and tactics were as clear as the alcohol she purportedly mixed. A coffee-shop regular was standing behind her in line about 3:45 p.m. and watched as she pulled two bottles out of her green Starbucks bag and placed them in the open-air fridge, police said.

The customer immediately alerted a store manager, apparently spooking Behbehanian into leaving, but not before an employee got a glimpse of her license plate, police said.

Employees immediately grabbed the bottles of orange juice and examined them. They realized the seals had been broken and smelled “something toxic,” Dwyer said.

They called 911, summoning San Jose police and the San Jose Fire Department, which brought its hazardous materials team. After clearing out the store, the hazardous materials technicians — who are trained to respond to events as high-level as the deployment of weapons of mass destruction — took samples of the liquid and ran it through a portable mass spectrometer that confirmed it was isopropyl alcohol, a common household solvent.

“It was significant enough to be seriously harmful. I can’t say it will cause death, but it’s a possibility,” said Capt. Cleo Doss, a fire department spokesman. “It depends on how much you consume. They could have a sip and stop, or someone who couldn’t smell it, maybe had a cold, might drink more.”

Using the information provided by the customer and the employee, police tracked Behbehanian to her home 5 miles west on Chambertin Drive and arrested her after questioning.

Her LinkedIn page states she has a master’s degree in physical chemistry and chemical engineering from Lehigh University in Pennsylvania and worked as a scientist, engineer or project manager for a string of high-profile corporations including Pfizer, Boston Scientific and Johnson & Johnson. At the time of her arrest, she was working at Janssen, a pharmaceutical subsidiary of Johnson & Johnson. This was confirmed by a company spokesman Tuesday.

Calls to Behbehanian’s home and relatives went unreturned Tuesday. Behbehanian declined a request for a jailhouse interview with this newspaper.

The alleged poisoning attempt occurred about the time students from Santa Teresa High School usually flock to the Starbucks, which is in the Santa Teresa Square shopping center across the street from the school.

A Starbucks spokesman lauded the multitude of acts that prevented anyone, including the students, from ingesting the spiked substance.

“We’re grateful to the customer who did the right thing,” Starbucks spokesman Zack Hutson said, adding the company thanked its employees “for doing all the right things,” including getting the suspect’s license plate number.

Hutson said the company is continuing to cooperate with the police investigation. After the incident, the Snell Avenue store pulled all the remaining juices from the refrigerator and destroyed them. He said other nearby Starbucks were notified and told to check all their juice bottles to make sure the seals weren’t broken.

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga. Contact Mark Gomez at 408-920-5869. Follow him at Twitter.com/MarkMGomez.