Praise be to Allah.
The marriage is valid and is not affected by that, so long as the necessary conditions were met, meaning that he married her with her consent, in the presence of her legal guardian (wali) and two witnesses, and with no impediment to the marriage. The fact that the mahr came from haraam sources does not affect the marriage. So if the conditions of marriage were met, and only some of the wealth was problematic, in that some of it was from haraam sources, this does not affect the marriage. He has to repent to Allah, may He be glorified and exalted, for what he took of haraam wealth, and he must return the wealth to its rightful owners if he stole it from someone or expropriated it from someone. He has to return it to them, and if it is not possible to do that, he should give it on behalf of the rightful owners to charitable causes, such as giving it to the poor and needy, or spending on the maintenance of roads and bathroom facilities near mosques, and the like. As for his marriage, it is valid. End quote.
Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him).
Fataawa Noor ‘ala ad-Darb, 3/1578.