Tabane ordered Lipolelo Tabane to be beaten to allow his current wife Masaya to become the first lady, Lesotho Police Commissioner Paseca Moquette said in a greeting.
Lipolelo Tabane was fatally shot by gunners near her home in the capital, Maseru, in June 2017.
She negotiated a divorce from Tabane before her death.
The documents say the prime minister and his wife allegedly met with the gang leader and promised them $ 177,000 and jobs to kill Lipolelo before he took office as prime minister, police said.
Tabain also shared his ex-wife’s home address with his killers, and they began monitoring Lipolelo’s movement, police said.
They tried to kill Lipolelo on June 12, but failed, and she reported the incident to police, according to Mokete.
Twice later, Lipolelo was postponed and killed on the way from a meeting with an unnamed mediator who is now a state witness.
The mediator is negotiating a truce between the two women in Ficksburg, a small town in neighboring South Africa, according to the report.
Two months after Lipolelo’s murder, Tabain married his current wife, Masaya.
Masaya is accused of killing Lipolelo 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 say he is immune because of his position.
Tabane resigned in May after months of pressure from his party to resign over his alleged involvement in the case.
He will be charged with murder now that he is no longer in power, Mokete said.
Police arrested Masaya again last week and her previous bail was revoked due to technical problems.
The court ordered a new bail and said a different judge should hear the case.