The perpetrators forced the main gate to Thoiry Zoo near Paris and broke through at least two other security barriers on Monday night last week, without disturbing five people who live on the grounds.
The animal, a four-year-old critically endangered southern white male named Vince, was attacked inside an area where at least two other rhinos are kept.
“Staff left the rhino enclosure on Monday. When they returned on Tuesday, an animal had been killed and its two horns had been sawn off,” a police spokeswoman told AFP.
Black market rhino horn sells for up to US$60,000 per kilo — more than gold or cocaine — with demand principally coming from China and Vietnam where it is coveted as a traditional medicine and aphrodisiac.