A Mexican photojournalist who had fled the most dangerous state in the country for news reporters under threats was found bound and shot to death on Friday night in an apartment in Mexico City along with four others.

The death of 31-year-old Ruben Espinosa is the seventh killing of a journalist so far this year in Mexico.

According to the press-freedom group Article 19, relatives of Espinosa identified his body on Saturday. They had reported him missing since 2 pm the day before when he sent a text message saying he was heading home. Reporters facing threats or working in dangerous regions in Mexico often practice a "security protocol" of checking in with colleagues or loved ones every few hours.

When Espinosa stopped communicating, his family reported him missing to local and federal authorities.

The photographer publicly denounced threats in a July 9 segment of online television outlet Rompeviento TV. He was among five homicide victims found on Friday night in an apartment in Narvarte, a middle-class neighborhood of Mexico City.

Press reports said the rest were women, three of whom were identified as roommates in the apartment and the fourth woman as the housecleaner. Espinosa had been tied up, showed signs of beating, and was shot twice, reports said.

The other victims had not been identified as of early Sunday.

At seven months on, 2015 is already more deadly for journalists in Mexico than all of 2014, in which five reporters were killed in the country. Mexico is ranked 148 out of 180 countries in the 2015 World Press Freedom Index published by Reporters Without Borders — below Honduras, Myanmar, and Venezuela.

Ruben Espinosa, right, said unknown men began following him and waiting outside his home in Xalapa, Veracruz. (Screenshot)

This year's rate of journalist killings is raising increasingly desperate calls of alarm among press freedom advocates about the climate of violence against reporters in Mexico.

Most of the homicides are by far concentrated in the Gulf coast state of Veracruz, home to several key eastern ports and a hub for drug- and human-trafficking. Since December 2010, when current Gov. Javier Duarte took office, 14 reporters who worked in the state have been killed or disappeared. Four have been killed this year.

Counts differ because watchdog groups have different parameters for confirmed journalist killings. In one case in early May, reporter Armando Saldaña Morales was shot four times outside his house in neighboring Oaxaca but hosted a news show on a radio station across the state line in Veracruz.

Espinosa is now the second Veracruz journalist tracked down and killed outside the state this year, and the first to be killed in Mexico City, making him the first "internally displaced" journalist murdered inside the Federal District.

Mexico's capital is considered a safe zone for unknown figures of reporters, activists, and merchants fleeing death threats or extortion in outlying states. "Article 19 sees with great worry that Mexico City could stop being the secure refuge that houses dozens of displaced journalists," the group's statement said.

Duarte, a member of the ruling Institutional Revolutionary Party (PRI), has sought to downplay the murders or blame other factors related to the victim's life or work for their deaths. On July 1, one month before Espinosa's killing, he warned a gathering of reporters to "behave," suggesting that many journalists in the state have links to organized-crime groups.

"I say it for your best interest, for your families, but also for me and my family, because if something happens to you, then I'm the one who gets crucified!" Duarte said, according to a recording of his speech.

Espinosa worked for the national newsmagazine Proceso, and the photojournalism agencies Cuartoscuro and AVC, among others. He did not cover crime or drug-trafficking, but said he focused on social movements, telling Rompeviento TV he had once been called an "anarchist photographer" by other local photojournalists.

"This is how Veracruz is now: the news media are at the service of the money, of corruption, and not just the directors, the people who go out as reporters and photographers," he said. "It's a prostitution of information that is devastating for society."

According to a biography published by a journalist group on Facebook, Espinosa had shot a cover of a February 2014 issue of Proceso that featured an unflattering portrait of Duarte with the headline: "Veracruz, State With No Law." The edition was said to especially infuriate Duarte; a massive buying of the issue quickly followed its publication, another tool used to suppress news in Mexico.

Colleagues also said he briefly worked for Duarte in 2009 when Duarte was a candidate for governor.

In early June, unidentified men began appearing near his house or following him. In one incident, three men watched him from a waiting taxi, while one of them shot photographs of Espinosa.

Espinosa belonged to a core group of journalists who organized for free-speech rights in Veracruz. On May 1, he helped place a plaque in honor of slain Proceso reporter Regina Martinez in a square of the state capital of Xalapa. By June 9, he said, the threats against him forced him to flee.

"There is no rule of law, there is no justice for a single murdered colleague," Espinosa told Rompeviento less than a month before his murder.