The U.K. Serious Fraud Office announced Oct. 18 it has closed its investigation into manipulation of the London Interbank Offered Rate (LIBOR), ending a probe that began more than seven years ago.

“Following a thorough investigation and a detailed review of the available evidence, there will be no further charges brought in this case,” the SFO said. The SFO makes charging decisions on the basis of the test in the Code for Crown Prosecutors, which specifies the evidence must support a realistic prospect of conviction and that the prosecution must be in the public interest. “In this instance, after an extensive and careful examination of the available evidence, the SFO found that no further charges passed the Code Test,” the agency said.

The SFO first launched its investigation into LIBOR manipulation in July 2012, resulting in charges against 13 individuals for conspiracy to defraud. In October 2014, Peter Johnson pleaded guilty to manipulating the U.S. Dollar LIBOR, the first criminal conviction for a LIBOR offense in the United Kingdom.

Jonathan Matthew, Jay Merchant, and Alex Pabon were convicted by a jury of the same charges in July 2016. In August 2015, Tom Hayes was convicted on eight counts of conspiracy to defraud in relation to the manipulation of Japanese Yen LIBOR. Between January 2016 and April 2017, six individuals were acquitted by jury of manipulating Yen LIBOR and two acquitted of manipulating U.S. Dollar LIBOR.

All strands of the SFO’s investigation into LIBOR manipulation are now closed. Aspects of the SFO’s investigation into the manipulation of the Euro Interbank Offered Rate (EURIBOR) remain open.

“The difficulties in proving cases against individuals have been apparent,” says Neil Williams, legal director of business crime solicitors Rahman Ravelli. “Considering the number of individuals charged, the SFO has achieved what can best be described as a limited amount of success. The outcomes have proved to be a mixed bag.”

The announcement makes clear, he says, the SFO is “prepared to settle for its limited success and move on.”