Apple co-founder Steve Jobs died of respiratory arrest linked to the spread of his pancreatic cancer, his death certificate has revealed. The certificate, filed in Santa Clara County, California listed his occupation as "high-tech entrepreneur". The Apple co-founder died on 5 October at the age of 56 at his home in Palo Alto. No post-mortem examination was performed, and Jobs was buried on Friday. The death certificate was released by the Santa Clara County Public Health Department on Monday the Associated Press news agency reports. According to the document, Jobs had a "metastatic pancreas neuroendocrine tumour" for the past five years. In 2004, he announced that he was suffering from pancreatic cancer. He had a liver transplant five years later. In January 2011 he took medical leave, before formally resigning as CEO in August and handing over his duties to Tim Cook. A statement from Jobs' family said they were with him when he died peacefully. Jobs died the day after Apple announced its latest iPhone, the 4S. On Monday Apple said it received more than one million pre-orders on Friday for the device, breaking a record set by the iPhone 4 when it was released in 2010.