A Contra Costa County sheriff's deputy lawfully shot and killed a suspect during an attempted arrest in 2018, according to the results of an investigation released Monday by the District Attorney's Office.

The investigation concludes that Deputy Matthew Gauthier did not break the law when he shot and killed Paul Ridgeway while trying to arrest him on an outstanding warrant on Dec. 5, 2018.

Gauthier shot Ridgeway eight times after Ridgeway allegedly fired a single shot from a 9 mm handgun, narrowly missing the deputy's head.

Ridgeway, an alleged member of the Family Affiliated Irish Mafia gang, was wanted on a no-bail warrant from another county for evading and resisting arrest, sheriff's officials said at the time of the shooting.

Gauthier tried to arrest Ridgeway at about 9:30 a.m. near Adelaide Drive and Pacheco Boulevard in an unincorporated part of the county near Martinez but Ridgeway allegedly ran when he saw the deputy coming, according to the District Attorney's Office.

Gauthier chased Ridgeway down, tackled him and pulled his "duty firearm" because Ridgeway was violently resisting arrest, prosecutors said in a news release Monday.

That's when Ridgeway allegedly drew his own gun and fired the shot at Deputy Gauthier's head.

Ridgeway died at the scene after being struck by Gauthier's return fire.

"The evidence shows that Contra Costa County Sheriff Deputy Matthew Gauthier acted in what he actually and reasonably believed to be self-defense and defense of others," according to the District Attorney's report.

"The examined evidence does not support the contention that the shooting of Ridgeway was criminal," according to the report.

The DA's office report can be found here.