A Florida man has been charged with first-degree murder on suspicion of killing and dismembering his wife, whose remains were found in suitcases at a beach last month, authorities said Thursday.

William Lowe, who was arrested Wednesday, is accused of killing his 80-year-old wife, Aydil Barbosa Fontes, Delray Beach police Detective Mike Liberta said in a news conference Thursday.

Investigators allege Lowe, 78, fatally shot Fontes in the head, dismembered her body at their apartment in Delray Beach and placed the remains in suitcases and a tote-like bag before discarding them at their local beach, Liberta said. Authorities believe Fontes was killed sometime between July 17 and July 20, police said previously.

During his first court appearance Thursday, Lowe pleaded not guilty to first-degree murder and abuse of a dead body, online court records show.

Marc Shiner, an attorney representing Lowe, told CNN in an email Thursday that Lowe is a "former Marine who honorably served our country." Shiner added the defendant "is looking forward for the entire truth to come out in the courtroom."

Lowe was being held without bond Thursday at Palm Beach County's jail.

Defendant seen at disposal location several times, affidavit says

The investigation started July 21, when police received calls from people reporting seeing suitcases they thought contained human remains at or near the Intracoastal Waterway at Delray Beach, about 9 miles north of Boca Raton, according to a probable cause affidavit.

The tips led detectives to three suitcases filled with human body parts that day. Police first found one suitcase floating in the water, and shortly after, they found two more suitcases at nearby locations along the beach, police have said.

A tote-type bag with more remains was found during a search of the waterway the next day, the affidavit reads.

"This is probably the worst I've seen," Liberta said.

Video surveillance of the area where the bags were found and witness statements helped police locate the defendant, Liberta said.

Witnesses told police they saw an older White man apparently look at one of the suitcases, and one witness said the man was there five or six times over a three-day period before authorities found the remains, according to the affidavit.

Witnesses also told police about a vehicle they'd seen a man with the same description get into near where a suitcase was dumped on the same day police found it, the affidavit states. A detective reported seeing a similar vehicle in the area, and the vehicle's tag revealed it belonged to Lowe, according to the affidavit.

Upon questioning, Lowe told police on Monday his wife had been in Brazil for "about three weeks," according to the document.

Police searched Lowe's apartment and spotted large amounts of blood in multiple areas in the home. A search of the suspect's storage unit revealed a chainsaw police believe was used in the dismembering, Liberta said.

"Detectives observed blood spatter throughout the residence to include the living room, dining room, hallway, both bathrooms and the master bedroom. Blood was detected in the master bath shower drain as well as the tub of the second bathroom," the affidavit states.

Police also saw drag marks in the living room, hallway and master bathroom along with numerous cleaning supplies, the affidavit notes.

Investigators don't know of a motive in the killing, Liberta said.