Parents of the 43 Mexican students who disappeared nearly six months ago are traveling to the United States to call on compatriots living there to boycott Mexico's June elections, a spokesman said Friday.

The spokesman, Felipe de la Cruz, said the aim was to pressure the Mexican government into keeping the investigation open, even though authorities want it closed.

"The Mexican government must understand that we will not rest until we find them (the students)," he said.

"All Mexicans, wherever they are, should know that you cannot trust the authorities or politicians."

Mexicans living in the United States can cast ballots in Mexican consular offices for the June 7 local legislative elections.

The missing students were from a teacher's college in Ayotzinapa in the southern state of Guerrero. They died in a night of protests on September 26 after being arrested by police in the nearby town of Iguala and handed over to a drug trafficking gang that killed them, burned their remains and threw them into a river, according to the official government account.

Relatives of the students and activist groups reject that account, noting that only one set of remains from the missing students has been positively identified.

De la Cruz said marches were envisioned in cities like Los Angeles, Dallas and Washington.

He said the parents remained in a state of mental turmoil.

"Some do not even want to eat. But still, the energy to protest remains strong," he said.

The parents have already held numerous marches, including in Mexico City and have traveled to Geneva in Switzerland to present their case before the United Nations Committee on Enforced Disappearances.

Human rights groups have criticized Mexico's government, saying the declaration that the students were dead was premature because unanswered questions remain in the case, especially since DNA tests have only confirmed one death.