ST. PAUL — A record number of Minnesota prison inmates were placed in solitary confinement last year.

The Minnesota Department of Corrections housed inmates alone and away from other prisoners more than 8,000 times in 2018, which is an increase over previous years. While the number of solitary sentences has fluctuated over the years, it has been going up steadily for the last two years, Minnesota Public Radio News reported. It is not clear what is contributing to the increases.

This year, the Minnesota Legislature passed a law requiring mental health screening for inmates being placed in solitary. The new law also requires the Corrections Department to report back to lawmakers regularly about the use of solitary confinement.

Republican Rep. Nick Zerwas of Elk River, one of the sponsors of the legislation, said he is concerned about the increasing numbers.

“The discouraging thing is it appears as though the use of solitary confinement appears to be going the opposite direction that a lot of advocates and legislators would like to see,” Zerwas said.

In June, the Corrections Department implemented new regulations that increase the maximum time allowed in solitary from 90 days to a year. The new rules also put in place levels of infractions designed to connect the infraction and the punishment. For example, one level allows up to 30 days in solitary for minor misconduct, while an inmate may be placed in isolation for up to a year for major offenses, such as homicide or sexual assault.

Corrections Commissioner Paul Schnell said the objective of the new rules is to control behavior. Ultimately, the department wants to provide incentives to help people get back into the general prison population, he said.

Solitary confinement sometimes is used to separate unruly prisoners from the general population, even if the behavior is triggered by mental illness. But inmates also are placed in solitary for other reasons.