It is narrated from Ibn Jurayj (may Allah have mercy on him) that he said: "I asked Ata (may Allah have mercy on him) about the statement of Allah: 'Do not kill game while you are in the state of Ihram, and whoever among you kills it intentionally...' (__QUR_N__ Al-Ma'idah: 95) — Is there also a penalty for the one who kills unintentionally?" Ata (may Allah have mercy on him) said: "Yes, this is out of reverence for the sanctities of Allah, and this is how it has been practiced."
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 878
Hadith Takhrijاسناده حسن اخرجه البيهقي: 5/ 180 - وفى المعرفة السنن والآثار له (3141) - وعبدالرزاق (8175) وابن ابي شيبة (15288)۔
It is narrated from Amr bin Dinar (may Allah have mercy on him) that he said: "I saw that people would give blood money (diyah) even in cases of accidental killing of an animal."
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 879
Hadith Takhrijاسناده ضعيف لعنعنة ابن جريج وهو مدلس: اخرجه البيهقي: 5/ 180 - وفى المعرفة السنن والآثار له (3142)۔
Ibn Jurayj said: Mujahid (may Allah have mercy on him) used to say that whoever among you (hunts) deliberately kills (the game) without forgetting, while in the state of ihram, and he has no other intention besides this, then he has made a mistake and it has become lawful, and there is no concession for him; and whoever kills it without remembering its sanctity or had some other intention besides this, then he has also made a mistake. This (mistaken) intention is such that for it, there is expiation with an animal of its like.
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 880
Hadith Takhrijاسناده حسن اخرجه البيهقى فى المعرفة السنن والآثار (15293)۔
It is narrated from Ibn Jurayj, he said: I said to Ata (may Allah have mercy on him): "And the compensation is obligatory, equivalent to the animal which he has killed, as judged by two just men among you (whether that compensation is from the cattle), to be brought as an offering to the Ka'bah, or as an expiation, to feed the needy." (Al-Ma'idah: 95) Ata (may Allah have mercy on him) said: Because he hunted that animal in the Haram and he also intends the House of Allah, so its expiation must also be given near the House of Allah.
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 881
Hadith Takhrijاسناده حسن اخرجه البيهقي: 1/ 180 ، 187 - وفى المعرفة السنن والآثار له، رقم : (3141)۔
It is narrated from Amr bin Dinar regarding Allah's command: "There is a ransom, so he may fast, or give charity, or offer a sacrifice." (__QUR_N__: Al-Baqarah: 196) that there is a choice in this; he may do whichever he wishes.
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 882
Hadith Takhrijاسناده ضعيف، لعنعة ابن جريج : اخرجه البيهقى 185/5 - وفى المعرفة السنن والآثار له (3175)۔