Sayyiduna Tamim ad-Dari (may Allah be pleased with him) says: I asked the Messenger of Allah (peace and blessings be upon him): O Messenger of Allah! If a person from among the disbelievers accepts Islam at the hands of a Muslim, what is the ruling regarding him? The Prophet (peace and blessings be upon him) said: “The one who brought him to Islam is closer to him, in both his life and his death.”
Hadith Referenceسنن دارمي / من كتاب الفرائض / 3066
Hadith Takhrijاس حدیث کی سند بمجموع الطرق صحیح ہے۔ دیکھئے: [بخاري تعليقًا فى الفرائض، باب إذا أسلم على يديه] ، [أبوداؤد 2918] ، [ترمذي 2112] ، [ابن ماجه 2752] ، [أحمد 102/4] ، [أبويعلی 7165]
Brief Explanation
(Commentary on Ahadith 3054 to 3066)
From the apparent wording of the hadith, it is derived that if a new Muslim has no heirs, then the right to his inheritance belongs to the person who brought him to Islam. And Allah knows best.