The investigation into the fatal shooting of a police officer from Gary, Indiana has led to three individuals being taken into custody.

The Chicago Tribune reported that according to Sheriff John Buncich, of the three people in custody, one man is “a person of interest” in the case. Officer Jeffrey Westerfield was in his patrol car when a motorist found him before 6 in the morning on Sunday.

A news conference done by the Police Chief, Wade Ingram, revealed Westerfield had been found unresponsive and the person who discovered him called 911.

The police had several leads before making their arrest.

Westerfield’s fiancée, Denise Cather, was said to be angry and she wanted to find the answers as to why her “best friend” was killed.

The Associated Press reported Westerfield’s 47th birthday was on Sunday. Earlier in the morning, he had gone to that area after receiving a call.

Westerfield was an officer for 19 years and he had four children before becoming engaged to Cather. A neighbor reportedly had seen fireworks from the family’s home on the Fourth of July.