The International Press institute (IPI) today called on Mexican authorities to conduct full investigations into the shootings of two journalists in the states of Oaxaca and Tamaulipas within 24 hours this week and not to rule out any theories prematurely.

According to news reports, unidentified motorcyclists shot Elidio Ramos Zarate*, who wrote under the pseudonym Guillermo Parie, in the neck on Sunday in Oaxaca in southern Mexico while he was photographing a robbery in progress at a convenience store.

The journalist had been covering ongoing teachers’ union protests, which turned deadly on Sunday when police reportedly shot at protesters blockading a major highway, killing six civilians.

Authorities noted that although they could not identify a clear motive for Ramos’ killing, he had connections to people who committed “illegal acts”, an apparent insinuation that they thought his murder may not be related to his work.

On Monday morning, teacher and freelance journalist Zamira Esther Bautista was shot as she entered her car to go to work at a school in Ciudad Victoria, the capital of the north-eastern state of Tamaulipas. Authorities there similarly linked Bautista to members of a criminal group, pointing to a card left at the scene of the crime making that allegation.

IPI Director of Advocacy and Communications Steven M. Ellis urged authorities to examine whether both journalists were killed as a result of their work.

“As we have observed in too many other cases of journalists murdered in Mexico, authorities’ initial public statements indicate that they may have already discarded the idea that these journalists’ reporting led to their killings,” he said. “Authorities have an obligation to consider all possible motives and prematurely ruling out journalists’ work as a possible motive contributes to the climate of impunity in Mexico. We call on authorities to uphold that obligation and to investigate these cases fully.”

At least seven journalists have been killed so far in Mexico this year. However, in a reflection of the impunity with which such crimes are met, IPI has only been able to link one to the journalists’ work: the murder of Anabel Flores Salazar, whose bound body was found alongside a highway in the state of Veracruz after she was abducted from her home by heavily armed men.

Despite initially highlighting Flores’ alleged relationship with a drug cartel member, Mexican authorities last month in a rare statement explicitly acknowledged that she was killed by a criminal organisation because of the impact of her reporting on that group.

In 2015, at least 11 journalists were killed in Mexico, but IPI so far has been able to link only two of those murders to the journalists’ work: the killings of Moisés Sánchez Cerezo in January and Armando Saldaña Morales in May. Nine other cases remain unclear as the result of inconclusive investigations.

*A previous version of the statement incorrectly identified the journalist’s first name as “Elpidio”.