Thabane has ordered Lipolelo Thabane to be hit to allow his current wife Maesaia to become first lady, said Lesotho Police Commissioner Commissioner Pasek Moqueta.
Lipolela Thabane was fatally shot dead by gunmen near her home in the capital, Maseru, in June 2017.
Before her death, she negotiated a divorce from Thabane.
Documents say the prime minister and his wife allegedly met with the gang chief and promised them $ 177,000 and a job that would kill Lipolela before his inauguration as prime minister, police said in a statement.
Thabane also shared his ex-wife’s home address with his killers and they began monitoring Lipolel’s movements, police said.
They tried to kill Lipolel on June 12, but failed, and she reported the incident to police, according to Mokete.
Then, two days later, they placed and killed Lipolel on the way from a meeting with an unnamed mediator, who is now a state witness.
The mediator negotiated a truce between the two women in Ficksburg, a small town in neighboring South Africa, the statement said.
Thabane married his current wife Maesaia two months after Lipolelo was killed.
Maesaia is accused of killing Lipolel and attempting to kill another woman, who was with the former first lady when she was killed.
The former prime minister has not been charged despite attempts by police to prosecute him. His lawyers claimed he had immunity because of his position.
Thabane stepped down in May after months of pressure from his party to resign over his alleged involvement in the case.
He will be charged with murder because he is no longer in power, Mokete said.
Police arrested Maesaiah again last week, and her previous bail was revoked due to technical problems.
The court ordered a new bail application and said the case must be heard by a different judge.