Less than 24 hours after a deputy discovered the body of fire battalion chief David Smith, the St. Tammany Sheriff's Office announced the arrest of 33-year-old Michael Lizana of Slidell and charged him with first-degree murder.

"This all began with a very alert resident, next door neighbor," said St. Tammany Sheriff Jack Strain.

Smith's neighbor called 911 yesterday around 3 p.m. and reported hearing gunfire. A deputy arrived at Smith's home and the sheriff's office said Lizana answered the door, claiming he was Smith's roommate.

"The deputy, given no evidence to think otherwise, left the scene, felt he needed to stay close to listen to additional gunfire or any potential evidence that may came forward," Strain said.

Instead, the deputy ran into one of Smith's fellow firefighters nearby and, after talking to him, became suspicious about what was going on at the house. When the deputy returned, Lizana answered the door again. This time, the deputy went in and discovered Smith's body in the trunk of the Camaro -- wrapped in plastic and shot four times.

"Each and every gunshot wound, we consider a fatal gunshot wound," said St. Tammany Parish Coroner Dr. Peter Galvan.

Investigators now believe Lizana came to the house, under the auspices of buying Smith's Camaro, which was up for sale.

"Somehow that morphed into this incredibly terrible crime and left David Smith, at a young age, and full of life and a public servant -- dead," Sheriff Strain said.

Smith's fellow firefighters were in mourning at St. Tammany Fire Protection District # 1 in Slidell. Flags there flew at half staff Tuesday afternoon.

"This is a family member to us," said Fire Chief Larry Hess, adding that Smith was a 23-year-veteran firefighter who was well-liked.

The department is now working with his family, as they all try to cope with their loss.

"We have casualty officers assigned, working with the family to assist them in making the final preparations," Chief Hess said.

Lizana is currently being held without bond at the St. Tammany Parish Jail.