According to a press release from the Santa Rosa County Sheriff’s Office, Robert Shane Lucas was found dead by staff members shortly after 5 a.m.

MILTON ― A Navarre man jailed for allegedly killing his mother-in-law in early February was found dead in his cell Friday, authorities say.

According to a press release from the Santa Rosa County Sheriff’s Office, Robert Shane Lucas was found dead by staff members shortly after 5 a.m.

Investigators are working the case as a suicide. No other information was immediately available.

Lucas had been indicted for first-degree premeditated murder; grand theft of a firearm; grand theft auto; fleeing or attempting to elude a law enforcement officer in an agency vehicle with lights and sirens activated at high speed; aggravated assault on a law enforcement officer; battery on a law enforcement officer; and resisting officers with violence.

Lucas’ mother-in-law, Carrie Lynn Brewer, was found dead Feb. 5 in her garage after she was reported missing just hours earlier.

Sheriff's deputies were called to 2212 Fulva Drive in Navarre that morning concerning the disappearance of the 57-year-old Brewer, who family members said was last seen Feb. 3. Deputies were called back to the same address several hours later after the family found notes that indicated a killing had occurred, the Sheriff’s Office said.

Brewer’s body was found under some household items in the garage after deputies executed a search warrant.

Sheriff Bob Johnson said in a press conference earlier that based on the evidence in the notes, the Sheriff’s Office issued an arrest warrant Feb. 6 for Lucas, 51, for first-degree premeditated murder.

On the day the warrant was issued, Lucas reportedly stole a 2012 Nissan Sentra, believed to be his mother-in-law’s car, from Navarre Beach.

Lucas was spotted later that afternoon on Bal Alex Avenue in Gulf Breeze. An ensuing high-speed chase lasted about 30 minutes over about 10 miles through school zones and subdivisions.

According to Sheriff’s Office spokesman Sgt. Rich Aloy, deputies deployed tire spikes on Whispering Pines Boulevard back in Navarre. Lucas ran over the spikes and lost control of the vehicle.

Lucas then turned his vehicle to face a deputy, who fired two shots. Lucas was not hit by the gunfire, but did suffer a head injury, the Sheriff’s Office said.

EMS took Lucas to Santa Rosa Medical Center, where he was to be treated before he went to the county jail.