The motive behind the fatal shooting of Dr. Elbert H. “Bert” Goodier III, 75, on Thursday apparently was rooted in a medical diagnosis given to his killer, a former patient who reportedly was mentally ill and who ultimately committed suicide, a Jefferson Parish Sheriff’s Office spokesman said Friday.

Medical privacy laws, however, prevented him from elaborating further, Col. John Fortunato said.

There was little else in the way of answers Friday for those who could not fathom an explanation behind the violence that ended the lives of Goodier — a husband, father, grandfather and esteemed urologist at East Jefferson General Hospital in Metairie — and Kenner resident John P. Thomas, a former commercial airline customer service representative who was a husband, father and grandfather himself.

According to a statement from his family, Thomas, 73, had long suffered from an undisclosed mental illness and “had been treated for years with both medication and therapy.”

Thomas also had been treated by Goodier, who formed part of the MD Anderson Cancer Network and earned recognition in 2001 as a “top doctor in New Orleans.”

It had been some time since Thomas had last gone to see Goodier — possibly a year, if not two, said multiple sources who didn’t want their names published due to the sensitive situation.

At some point, though, Thomas learned of a diagnosis with which he took issue. It wasn’t clear if Goodier was the doctor who informed Thomas of the diagnosis.

However, Fortunato said, “apparently, (Thomas’) issue with the doctor ... had something to do with his diagnosis.”

Thomas “had never been violent nor expressed a desire to harm others,” according to the statement his family released Friday afternoon.

That changed about 2 p.m. Thursday, when Thomas walked into Goodier’s second-floor office at 4224 Houma Blvd. with a handgun. Thomas barged into a room where Goodier was treating a patient and shot the physician near the side of the nose, killing him, investigators said.

He then headed to a Wendy’s about a block away, where he stuck his gun in his mouth and pulled the trigger, killing himself, as sheriff’s deputies entered the restaurant.

He did not have a cellphone, identification, a suicide note or even car keys on his person, and it wasn’t clear how he got the gun used in the incident, sources familiar with the investigation said.

The various unknowns initially caused some speculation that Goodier’s unknown killer was a patient who had showed up at the doctor’s office earlier in the day asking for a pharmaceutical drug and was refused. However, that man was discarded as a suspect when authorities went to his family’s residence and he was there, alive.

Authorities weren’t led to Thomas as the killer until after his family called the Sheriff’s Office, reported him missing and said they feared he might have shot Goodier as well as himself.

“There are a whole lot of uncertainties,” one source said. “This was crazy from start to finish.”

In the midst of all that, both Goodier’s and Thomas’ loved ones took the time to issue statements Friday about the difficult grieving period they were only just beginning.

“Our hearts go out to the Goodier family. Please know you are in our thoughts and prayers,” Thomas’ survivors said in their statement. “We knew Dr. Goodier to have been an excellent doctor who treated (Thomas) with skill and compassion.”

They said they decided to mention Thomas’ mental issues publicly “not to justify his actions but to help explain them.”

“We are profoundly saddened by what has happened,” the Thomas family said. “As a family, we are in shock. We appreciate your understanding, as you provide us with the opportunity to process what has happened and mourn.”

For their part, Goodier’s family members described themselves as “devastated about the tragic loss of such a wonderful husband, father, grandfather and physician.”

They thanked community members for “the outpouring of support” they had received as word of Goodier’s death spread, and they also asked for privacy as they mourn. His survivors include his wife, three children and five grandchildren.

An obituary of Goodier released by Lake Lawn Metairie Funeral Home invited friends and family to a funeral Mass at 1 p.m. Monday at St. Clement of Rome Catholic Church, 4317 Richland Ave. Visitation will begin at 10 a.m., and Goodier will be buried at Hope Mausoleum, 4841 Canal St. in New Orleans, the obituary said.

The obituary noted that he graduated from Jesuit High School in 1957, Loyola University in 1963 and LSU Medical School in 1967 before embarking on a nearly 50-year career as a doctor, much of which he spent at East Jefferson.

It said he was a lieutenant commander in the Navy during the Vietnam War, “an avid LSU fan,” a Krewe of Hermes member and a regular participant in the silent Jesuit retreats held at the Manresa House in Convent.

Fellow East Jefferson urologist Dr. Walter Levy described Goodier on Friday “as one of the good people in this world.”

Levy said he looked forward to regular lunches with Goodier, during which they would put work aside to discuss Goodier’s kids and grandkids and LSU football.

“I obviously won’t ever do that again, and that’s a profoundly difficult thing,” Levy said. “You snap your fingers, and it’s just gone. I am still trying to wrap my mind around it.”

Staff writer Matt Sledge contributed to this report.