Tokyo (CNN) -- It's a case that could make you think twice before leaving your footwear unattended.
Japanese police say they have arrested a man over allegations he tried to kill a female colleague by putting hydrofluoric acid, a highly corrosive chemical, in her shoes.
The alleged attack, which police say took place in December, caused gangrene to develop in the toes of the woman's left foot.
To deal with the problem, doctors had to remove the tips of five of her toes, said Teyuaki Harano, deputy chief of police in Gotemba, the city less than 100 kilometers southwest of Tokyo where the suspect, Tatsujiro Fukazawa, was arrested Thursday.
Fukazawa, 40, denies the allegations of attempted murder, according to police.
Police officials believe the suspect had "romantic feelings" toward the victim, Harano said. He didn't elaborate on why those feelings might be connected to the alleged acid attack.
Japanese media reports said that Fukazawa and the victim both worked in a laboratory at a company that makes carbon-fiber products.
It's very common for Japanese lab or factory workers to take off their shoes when entering controlled environments in such facilities.
Police declined to provide further details on the circumstances of the alleged attack or the place where the two people worked.
Hydrofluoric acid, also known as hydrogen fluoride, is "a very strong inorganic acid," and skin contact with it requires immediate hospital treatment, according to the U.S. National Library of Medicine.
"Fingertip injuries from hydrogen fluoride may result in persistent pain, bone loss, and injury to the nail bed," the U.S. Centers for Disease Control and Prevention (CDC) say.
The acid is used in the manufacture of many products such as plastics and electrical components, as well as for etching glass and metal, according to the CDC.
CNN's Yoko Wakatsuki reported from Tokyo, and Jethro Mullen reported and wrote from Hong Kong.