By 2014, four Karolinska doctors started to question Macchiarini's transplantation of plastic tracheas and raised the alarm at Karolinska University Hospital and Karolinska Institute. They suspected that Macchiarini had been lying in his scientific papers and that patients' lives were being put at risk by a technique which had not been properly tested or investigated beforehand. But still his employer, the Karolinska Institute, defended him and claimed nothing was amiss.