I inform you hereby that your proposal [to destroy the material seized] has been approved by the President of the Republic. Secretary General Jean Collin 17/01/1989
On 31 December 1988, the Senegalese Police (Gendarmerie) requested the authorization to destroy the explosives seized at Dakar airport on 20 February 1988.
(Note. On 28/12/1988, AAIB Michael Charles announced that two pieces of metal recovered in the wreckage of PA 103 provided evidence of a plastic explosive.)
This authorization was granted by Jean Collin in a letter dated 17 January 1989.
The document and its translation can be found on this page
For those who have read the book of President Abdou Diouf, it is far from obvious that the President actually approved that request. (See page 294) In any case, President Diouf replaced Jean Collin by André Sonko on 27 March 1990.
But the real question is this: Where is the MST-13 timer? To this day, nobody knows what happened to it?
Both CIA agents [Kenneth Steiner and Warren Clemens] involved in the case have alleged that the Libyans took it back as they returned home! That allegation did not amuse the Senegalese authorities.