A:
On turning to Allah with sincere repentance with regards to the ill-gotten money, it is obligatory for one to get rid of such evil money. In case he is not able to define the ill-gotten money, he can give out what he thinks to clear himself from such guilt. This is to be followed if his sins have not caused him to leave Islam.On committing sins that make a person leave Islam such as the abandonment of Salah, according to the most preponderant opinion of scholars, even if such a person does not deny (Part No. 24; Page No. 366) its obligation, repentance can be realized by performing Salah and embracing Islam again. This is because Islam wipes out all that has gone before it. Also, one is not obliged to get rid of the money he got before adopting Islam. This is because Allah (Exalted be He) says about the disbelievers,
Say to those who have disbelieved, if they cease (from disbelief), their past will be forgiven.
As mentioned in the Sahih (Authentic Book of Hadith), the Prophet (peace be upon him) said,
Islam wipes out all that has gone before it (previous misdeeds). And penitence also wipes out all that has gone before it.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.