Hertfordshire Constabulary has contacted the Independent Office for Police Conduct (IOPC) following the death of a 27-year-old man from Hemel Hempstead.
The man was taken ill on Thursday, February 10 while being detained by the police in Cotterells, Hemel Hempstead.
Herts Police spokesperson said: “The IOPC was informed of the incident, which is standard procedure when a person who has been in recent contact with the police dies.
“Our thoughts are with the man’s family at this difficult time and we will be doing everything we can to assist with the IOPC investigation to establish the exact circumstances surrounding his death. At this stage it would be inappropriate to comment any further.”