And these sentiments are widespread, felt beyond the world of journalism. State oppression has decimated civil society and negated years of social progress, casting a pall on the public mood. The diminished spirit threatens to stifle innovation, professionalism and the long-held “can-do” ethos among the Chinese. The consequences may be ruinous to the leadership’s aspirations for China to become an economic superpower.

The investigative journalism boom had emerged from a propitious alignment of political and social conditions. The government had decided, as part of a vast rollback of economic control, to cut subsidies to state newspapers, forcing them to seek more of their revenue from sales. Editors, in turn, felt they had a license to push boundaries. Sensing a public appetite for hard-hitting watchdog journalism, they encouraged reporters to pursue stories with an eye to social impact.

The fruit of this labor fueled hope among citizens for social change. Reports disclosing the true scale of the 2003 SARS epidemic pressured evasive officials into taking action. An inquiry into an unexplained death in police custody led to the scrapping of a nationwide illegal detention system. All over the country, corrupt bureaucrats were brought down for crimes from illegal urban demolitions to embezzling state funds that they could no longer sweep under the rug owing to the new army of whistle-blowers.

Riding on those successes, regional newspapers like Southern Weekly, Southern Metropolis Daily, and Dahe Daily rose to national prominence. Despite their government affiliations, these papers enjoyed relative freedom thanks to liberal-minded political leaders who considered investigative reporters political allies. The few muckraking journalists who lost their jobs in these years were far outnumbered by those who carried on, united in their belief in the importance and power of their work.

As censorship increased under Mr. Xi, investigative journalism lost its edge — and then its audience. Dwindling revenues forced newspapers to lay off investigative journalists and, at times, to eliminate entire departments. The number of investigative journalists dropped by more than half in six years, to a total of 175, according to a report from Sun Yat-sen University in December.