Genocide is never allowed in Islam. Even killing someone based on suspicion is prohibited.

عن عائشة قالت قال رسول الله : “أدرئوا الحدود عن المسلمين ما استطعتم فإن كان له مخرج فخلوا سبيله فإن الإمام أن يخطئ في العفو خير من أن يخطئ في العقوبة”.

Narrated by ‘Aishah ( R):

That the Messenger of Allah (PBUH): “Avert the legal penalties from the Muslims as much as possible, if he has a way out then leave him to his way, for if the Imam makes a mistake in forgiving it would be better than making mistake in punishment”. {Tirmizi: 1/26}

“أن الحد لا يثبت عند قيام الشبهة”. (رد المحتار)

Penal code would not apply if there is space for suspicion {Shami:6/25}

عن إبراهيم قال، قال عمر:”لأن أعطل الحدود بالشبهات أحب إلي من أن أقيمها بالشبهات”

It is narrated from Umar (R) that I would better to leave someone on suspicion rather than punishing based on suspicion {Hashia e Hidaya: 1/493}