(Reuters) — Britain’s Serious Fraud Office has closed its four-year bribery and corruption investigation into the U.K. subsidiaries of KBR Inc., a U.S.-listed engineering, procurement and construction company.

The investigator and prosecutor said on Thursday that it had not uncovered sufficient evidence to pursue the case.

KBR said it was “pleased and supportive” of the decision, which followed similar announcements by the U.S. Department of Justice and the Securities and Exchange Commission that put “a final conclusion to this matter.”

The closure of the case is the latest in a string of major investigations shut under SFO head Lisa Osofsky. Inquiries into British American Tobacco, aero engine maker Rolls-Royce and drugs company GlaxoSmithKline have all been dropped over the past two years.

Some lawyers say lengthy cases need to have their wheels regularly kicked as the SFO can only proceed with criminal investigations if the evidence supports a realistic prospect of conviction and if a prosecution is in the public interest.

“Closing cases that are ultimately ‘without legs’ evidentially is the right thing to do,” said Sarah Wallace, a lawyer at Constantine Law, adding that this would help to clear desks and capacity for an expected wave of enforcement activity over pandemic-related wrongdoing.

The SFO’s investigation into KBR ended in a tussle at the U.K. Supreme Court last month over whether it was wrong to try and compel foreign businesses to hand over documents held overseas.

In a blow to the agency, senior judges ruled that it had no extraterritorial reach -- although they confirmed the agency’s power to compel U.K. companies to repatriate documents held overseas.

The SFO said the ruling had no bearing on its decision to close the KBR investigation.

The KBR investigation was originally related to a sprawling inquiry into Unaoil, a Monaco-based oil and gas consultancy, which has led to four men being convicted in Britain of bribery to secure contracts worth $1.7 billion for Unaoil and Western, blue-chip clients.

Unaoil’s former chief executive and chief operating officer, Cyrus and Saman Ahsani, in 2019 pleaded guilty in the United States to being part of a 17-year scheme to pay millions of dollars in bribes to officials in the Middle East, Africa and Central Asia.