After the Cathars were accused of murdering a papal legate in 1208, Pope Innocent III declared the Albigensian Crusade.[104] Abuses committed during the crusade caused Innocent III to informally institute the first papal inquisition to prevent future massacres and root out the remaining Cathars.[105][106] Formalized under Gregory IX, this Medieval inquisition executed an average of three people per year for heresy at its height.[106][107] Over time, other inquisitions were launched by the Church or secular rulers to prosecute heretics, to respond to the threat of Moorish invasion or for political purposes.[108] The accused were encouraged to recant their heresy and those who did not could be punished by penance, fines, imprisonment or execution by burning.[108][109]