Derek Chauvin -- the former Minneapolis PD officer charged with the murder of George Floyd -- has a new jail cell for now ... he's been transferred to a maximum-security prison.

Chauvin's been sent to the Minnesota Correctional Facility-Oak Park Heights near the city of Stillwater, after spending part of Sunday at the Hennepin County Jail. It's protocol for inmates to get new mug shots when they're transferred.

The ex-cop was originally held at the Ramsey County Jail after being arrested Friday and charged with third-degree murder and manslaughter in Floyd's death.

According to the Department of Corrections ... the Oak Park Heights prison is the highest custody level in Minnesota's system, and several inmates -- like Chauvin -- need a higher level of security.

DOC Commissioner Paul Schnell says this kind of transfer is not uncommon -- the same thing happened when former Minneapolis cop, Mohamed Noor, was taken into custody in the killing of Justine Damond -- and it was requested by the Hennepin County Sheriff.

Chauvin was one of 4 officers fired over Floyd's death, but so far he's the only one arrested and charged. Chauvin was the cop who pressed his knee on Floyd's neck for close to 9 minutes ... including more than 2 minutes after Floyd was unresponsive.

Still, there's outrage that the other cops have still not being arrested. The entire incident -- along with other cases of black people being unjustly killed -- has incited several straight days of protests, riots, looting, violence and destruction across several major cities in the U.S.