The killing threatened to unleash another round of scandals in the Salinas family, which has already been touched by corruption and murder, as authorities revealed that French authorities had an outstanding request to locate Enrique Salinas at the time of his death.
The mystery thickened when the head prosecutor of Mexico State, Alfonso Navarrete Prida, revealed that the dead man had apparently written a letter in which he "described the financial difficulties he had been suffering since 1995," the year after his brother's 1988-1994 administration ended.
President Vicente Fox tried to downplay the implications of the killing, saying "the fact that he bore the last name 'Salinas de Gortari' doesn't necessarily mean politics was involved."
But the Salinas clan's personal information has often had huge implications for Mexico.
Raul Salinas, another of the ex-president's three brothers, is serving nearly 27 years in prison for masterminding the murder of his former brother-in-law. Swiss and Mexican authorities struggle to determine how he came by tens of millions of dollars in Swiss accounts.
The former president is widely blamed for the economic collapse that immediately followed his term. After leaving office, he spent several years in self-imposed exile in Ireland, but has spent more time in Mexico in recent years.
A businessman and engineer who had lived an hour's drive outside Mexico City in Cuernavaca, Enrique Salinas stayed out of politics and kept a relatively low profile.
But he was called in 1996 to testify in Paris as part of an investigation looking into possible embezzlement of public funds and drug trafficking activities. Officials never brought any charges.
More recently, Enrique Salinas appeared to be under financial pressure from failed business ventures and the expense of supporting children and a divorced wife, Navarrete Prida said on Tuesday in a radio interview.
Navarrete said he has solicited information from the federal Attorney General's Office about a French request to Interpol on Nov. 22 to locate Salinas.
"So far the investigations do not report even the existence of an open file against Enrique Salinas" in Mexico, Navarrete said. "And investigations by foreign governments, what's being reported is a request for a location — not an arrest warrant.
"What we do have for sure is, yes, there is a homicide whose fundamental tinge suggests extortion."
On Tuesday, investigators examined evidence collected since the body's discovery on Monday in Huixquilucan just west of Mexico City.
A cellular phone was found in the car and investigators said they were studying the images captured by a street-surveillance camera that showed someone getting out of the car in which Salinas' body was found with a plastic bag over his head. The figure then got into another dark-colored vehicle and left.
President Vicente Fox said on Tuesday that the killing didn't appear to be politically motivated because Salinas wasn't a public official.
Carlos Salinas on Tuesday said he was confident authorities would solve the killing would be solved by authorities, during a viewing for Enrique in Mexico state. A private funeral was being held on Tuesday.