The UK’s Serious Fraud Office (SFO) which investigates and prosecutes serious or complex fraud, bribery and corruption has dropped two long-running investigations into mining firms Rio Tinto PLC and Eurasian Natural Resources Corp. (ENRC), bringing an end to the about six years of painstaking investigation into Rio Tinto.

The SFO disclosed this in a statement on their website, noting that it has closed its 2017 Rio Tinto investigation into allegations of corruption in Guinea after an internal review found it was not in the public interest to continue. No charges against individuals had been made.

Separately, the agency also announced it has closed a decade-long criminal investigation into ENRC citing “insufficient admissible evidence to prosecute.” The probe, one of the prosecutor’s longest, has been mired in controversy and allegations of reckless investigations against the SFO. It had focused on suspected bribe payments to secure mining contracts in the Democratic Republic of Congo between 2009 and 2012.

Meanwhile, the discontinuity of the investigation is another setback for the agency that’s expended years prosecuting suspected corruption across the commodities industry. The SFO, which both prosecutes and investigates the most serious white-collar crime in Britain, has a long list of recent missteps in the last few years. It has been accused of botching investigations, seen trials collapse, and a government-requested review that found the SFO’s failure in its Unaoil bribery case were caused by “cultural issues” in the agency.

Rio Tinto said in a statement after the announcement that it is “committed to conducting business to the highest standards of integrity.” However, the Australian Federal Police’s investigation into the case remains ongoing.

Criminal Investigation Into ENRC

Since the SFO began its criminal investigation into ENRC, the Kazakhstan mining firm has initiated at least 16 legal proceedings in the US and UK against lawyers, investigators, contractors, journalists, a former SFO official and the SFO itself, according to anti-graft campaigner Spotlight on Corruption.

“ENRC is pleased that the SFO has finally closed its investigation and that the SFO is taking no further action in respect of this matter,” a spokesperson said.

It can be recalled that owing to the SFO investigations, the mining company ENRC at the centre of a row over professional privilege called for an independent inquiry into the Serious Fraud Office (SFO), accusing the office of failing to investigate a whistle-blower’s letter.

ENRC also filed an application at the High Court seeking pre-action disclosure from the SFO for a ‘number of claims including misfeasance in public office’. The High Court application seeks disclosure of, among other things, the notebooks of the SFO’s former chief investigator and accuses the office of a breach of contract and fiduciary duties.

An SFO spokesperson said “We see no merit in the application issued by the ENRC. Before they made this application for a narrow range of additional information, we told ENRC that we will be able to provide it if it exists. We remain satisfied that the issue was handled appropriately.”

However, it is yet to know if the actions of ENRC indeed forced the SFO to drop the investigations.