The investigation was announced by Dr. Rita Singhal, chief medical officer of the county Department of Public Health.
"We are early in the investigation and do not have additional details available at this time," Singhal said. "As soon as details become available, we will share them while maintaining confidentiality and privacy."
The death is the second in the United States being investigated as possibly caused by monkeypox, according to Singhal.
5 things to know about contracting monkeypox
She said the county will be working with the U.S. Centers for Disease Control and Prevention and the state as it investigates the circumstances of the person's death.
The U.S. leads the world with monkeypox infections - as of Wednesday, 21,274 cases had been reported - with men accounting for about 98% of cases and men who said they had recent sexual contact with other men about 93% of cases.
Monkeypox, which can cause a rash, fever, body aches and chills, is spread through close skin-to-skin contact and prolonged exposure to respiratory droplets. The Centers for Disease Control and Prevention has recommended that men or transgender people who have had multiple male sex partners consider vaccination.
City News Service contributed to this report.