Is it permissible to partner in a business venture with a friend who works at the Central Bank and his wife, a journalist, and can a portion of his contribution be considered from his wife's money if there is any suspicion?

If it is established that your friend's entire wealth is illicit (haram), then it is impermissible to partner with him. However, if his wealth is mixed between licit (halal) and illicit, then partnering with him is reprehensible (makrooh), with the degree of reprehensibility varying according to the proportion of illicit wealth within it. There is no difference in this regard whether the wealth belongs to him, or to his wife, or to both of them. Jurists have explicitly stated the reprehensibility of dealing with someone who does not abstain from usury or whose wealth is mixed, and the impermissibility of trading with someone whose entire wealth is known to be illicit. Ascertaining the status of the wealth is dependent on the inquirer's investigation and verification.