Salut,
J’ai commencé la traduction :
On the tenth of March, during a cold and wet night, a murder (ou « a crime », murder c’est meurtre) had been committed, around twenty-one o’clock, at Guilvinec’s harbour. The victim was Mister Broutz.
A eyewitness had see all; so the murderer went in search of him.
Lieutenant Colombo arrived on the murder’s scene in his light grey convertible 403 Peugeot. Smoking his eternal big cigar. Scratching his head with his right hand, he was thinking that the murderer has killed with a butcher cleaver.
He asked the neighbours for information to know if they had seen someone or some unusual car go by in front of their home. They answered no, because at this hour, they were already to bed.
But the lieutenant kept on searching information to Mister Broutz’ secretary. Mister Broutz was a famous writer, renowned for the best detective novel of year 2000.
I hope you keep on translating

. Try to make it yourself because it’s better to learn foreign language. Continue avec un dictionnaire seulement. Si tu as une question n’hésite pas.
PS : Pour les conjugaisons, il y a peut-être des erreurs…..