The prime minister of Lesotho, Thomas Thabane, is to be charged with the murder of his estranged wife Lipolelo Thabane, police announced.

The 80-year-old announced he would be stepping down in July because of old age, without commenting about the case.

Thomas Thabane’s current wife, Maesaiah, has already been charged with the murder.

The prime minister would be the first leader in southern Africa to be charged with murder while in office, in a case that has shocked the tiny mountain kingdom.

Lipolelo Thabane, 58, was shot dead two days before her husband became prime minister in 2017.

At the time, Thomas Thabane described his wife’s killing as “senseless” but police now accuse him of being involved in her killing.

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Deputy Commissioner of Police Paseka Mokete was quoted by Reuters as saying: “The prime minister is going to be charged with the murder.

“The police are preparing directives and he will probably be charged tomorrow [February 21].”

Thomas Thabane said on state radio that he had served the nation “diligently” and he would retire at the end of July, Reuters reports.

He was quoted as saying: “I’ve worked for a peaceful and stable Lesotho. Today… at my age, I have lost most of my energy.”

The ruling All Basotho Convention had given Thomas Thabane a deadline of February 20 to resign.

Lipolelo Thabane was gunned down at close range on the side of a dirt road while returning to her home in a small village on the outskirts of the capital, Maseru.

She was involved in bitter divorce proceedings with Thomas Thabane when she was killed.

At the time, the prime minister was living with Maesaiah, 42, as if she were his wife.

However, Lipolelo Thabane had already won a separate legal battle to be recognized as first lady, as opposed to Maesaiah.

Maesaiah Thabane accompanied the prime minister to his inauguration, following his estranged wife’s death.

Two months later Maesaiah and Thomas Thabane got married in a Catholic ceremony held at a packed stadium in Maseru.

Maesaiah Thabane was charged with her rival’s murder on February 5, and is out on bail of about $67.

The prime minister’s current wife has also been charged with the attempted murder of a family friend Thato Sibolla, who was with Lipolelo Thabane at the time of the shooting and is expected to be a key witness in the murder case.

Maesaiah  Thabane has not yet been asked to enter a plea.