Jalisco state prosecutor Eduardo Almaguer said at a news conference that preliminary results of the investigation indicated that all involved - kidnappers and kidnapped - were members of criminal organizations.
Prosecutors in the western state of Jalisco said two SUVs carrying an unknown number of gunmen arrived around 1 a.m. at the La Leche restaurant on the city's main boulevard.
At least 35 people, 20 of them foreigners, were still trapped inside the restaurant.
U.S. authorities on Wednesday seized a cross-border tunnel that ran the length of four football fields from a restaurant in Mexicali, Mexico, to a newly built house in Calexico, California.
The court filing asks a judge to throw out Trump's lawsuit against restaurateur José Andrés, who denied to run a restaurant in Trump's new hotel after harsh comments on Mexican immigrants.
Police have confirmed four of the five worked at Kim's Garden in Novi and all lived in the basement of their restaurant owner's house where they perished Sunday morning.
Andrés, who is a Spanish immigrant, issued a statement Wednesday citing Trump's statements "disparaging immigrants" in his decision to cancel plans for an eatery at the Trump International Hotel.