Mysteries - The menu

Six o’clock pm. Finally, time to rest from a day full of processes, paperwork, photos, surveys, investigations without solution in sight, but which could not be forgotten.
Inspector Martins tied up the mess that was on top of his desk as usual. He opened the top drawer of his desk and threw all the papers in it. He put the phone in the upper right and the lamp in the upper left. He went to the cloakroom and put on his long black raincoat. With the suitcase in his hand he headed to the door and disappeared.
He reached home around 6.30 and, before taking a shower, he sat on the sofa. With the command he connected the TV. The news had just started. World news, crime, break-ins, civil disorder. No! It was not possible. He went to the kitchen and noticed that he had nothing to eat. It was decided: he would take a shower, wear pleasant clothes and have dinner out. That was a great idea.
He left home around 7. 30 and drove his car to the restaurant. He was not a frequent customer, but he always liked the food there and, when possible, this was the chosen location for a more quiet meal. There were few customers and the location was calm, in a quiet city zone.
He chose a table near the window. From there he could admire the green landscape of the park and at the same time he had an overview of the whole restaurant room. After choosing his favourite meal, pork chops with mushrooms, accompanied by a mature red, he began with the snacks.
Suddenly, he heard a cry on the opposite table. Someone was lying on the table, fainted. The employees quickly went to the table, as well as the Manager and Inspector Martins. The man was dead. The employee that was closer exclaimed that he suddenly fainted, for no apparent reason. It could have been a heart attack. Inspector Martins told them to close the restaurant. No one could enter or leave without his authorization. And that someone would call 911 and the local police.
While waiting, he spoke to the employee who had served the unhappy customer. He had nothing to clarify. The customer had a fish, salad and a bottle of water. And soup. Inspector Martins also had had soup, although a bit unsalted.
Inspecting the table he noticed the knife, fork and spoon carefully placed, the napkin, the glass of wine, the glass of water, the entries and pepper.
He decided to take a look at the other tables but they were no different from this one: the same plates, napkins, cups, salt and pepper.
Was it natural death or murder?