(Corrects headline and paragraph 3 to make clear investigator was not convicted of bribery)
* Detective convicted of witness tampering
* Ex Liberian President convicted of war crimes
By Tommy Trenchard
FREETOWN, Feb 8 (Reuters) - An investigator hired by former Liberian President Charles Taylor's defence team will spend 30 months in jail for tampering with prosecution witnesses in the landmark case, a U.N.-backed court decided on Friday.
Ex-President Taylor was convicted in April of war crimes and crimes against humanity for his role in supporting rebels during Sierra Leone's civil war, the first time a head of state has been found guilty by an international tribunal since the Nazi trials at Nuremberg.
One of his defence team's investigators, Prince Taylor - no relation to the former president - was arrested late last year and later convicted on five counts of interfering with witnesses.
"The message...must be clear and must be emphatic," said presiding Judge Teresa Doherty on Friday during the sentencing. "Justice can only prevail when witnesses can speak out without fear or favour."
The sentence was lower than recommended by the prosecution. Factors taken into account by the judge included the defendant's clear past record, his "excellent" support of his family, and his active role in the community and the church.
Charles Taylor was sentenced to 50 years in prison for supporting RUF rebels in Sierra Leone's civil war. The court ruled he had funded and armed the notoriously brutal rebel group, often in return for so-called blood diamonds.
The rebels used drugged child soldiers they had abducted from their families to commit atrocities including rape, enslavement, beheading, disembowelment and maiming. Some 50,000 people died in the war, which ended in 2002.
Charles Taylor's legal team launched appeal proceedings against the sentence in January. The U.N.-backed court was established to try those deemed to bear "greatest responsibility" for crimes committed in the West African war. (Editing by Richard Valdmanis and Roger Atwood)