The Denver Sheriff’s Department is investigating why immigration authorities weren’t notified of the release of a jail inmate until about an hour after he had already left.

Ivan Zamarripa-Castaneda of Mexico is charged with vehicular homicide in a hit-and-run crash that killed a truck driver. The 26-year-old was released from Denver’s jail Saturday after posting bond.

The sheriff’s department says the delay was “unacceptable” and that the sheriff has ordered an immediate internal review.

The release comes after Denver’s jail was criticized for giving immigration officials about a half-hour’s notice before releasing an auto theft suspect, Ever Valles, they had expressed an interest in. He was later involved in a fatal robbery.

Denver does not hold inmates for immigration officials unless they have a warrant but does provide notice of releases.