Context:
A man just died from a poison-induced heart attack after drinking a cup of tea that his wife served.
1 : Il a dû être empoisonné. Il venait de boire du thé, non ? Son épouse vient tout juste de nous servir du thé ! Le voilà, votre poison !
His wife first served tea, and then the husband drinked it. Despite the order in which the two events occurred, the present tense {vient tout juste de} is used for the more previous act of his wife having served tea, whereas the Imparfait {venait de} is used for the more recent act of the husband having drunk it.
At least in theory, the two tenses should be swapped around:
2 : Il a dû être empoisonné. Il vient de boire du thé, non ? Son épouse venait tout juste de nous servir du thé ! Le voilà, votre poison !
I wonder why this apparently contradictory usage of tense happens here.