2010 and, in a farewell interview, listed his top three achievements as the implementation of cell phone blocking technology in prisons, better enforcement by the Probation Service of sentence compliance, and the establishment of the Professional Standards Unit to investigate corruption by prison officers. During Matthews' tenure there was public concern about the management of the department. Simon Power, opposition spokesman for justice from 2006 through to 2008, made a number of calls for an inquiry into Corrections, but none was held. In 2009 Matthews' leadership was questioned by the new Corrections Minister, Judith Collins, after a run of bad publicity that included the murder of 17-year-old Liam Ashley in a prison van; the murder of Karl Kuchenbecker by Graeme Burton six months after he was released on parole; and the Auditor General's critical report on the Probation Service's management of parolees. Matthews exacerbated speculation about his leadership during the Burton debacle when he claimed: "There's no blood on my hands". After the Auditor General's report was released in 2009, Collins refused to express confidence in Matthews and media commentators expected him to resign. However, Matthews refused to do so and served out his term; on his retirement he admitted he had dealt with so many crises, the department was like a "landmine". Ray Smith, former deputy chief executive of Work and Income and former deputy chief executive of the Ministry of Social Development's Child, Youth and Family, was chief executive from 2010 to 2018. Deputy Chief Executive Jeremy Lightfoot and National Commissioner Rachel Leota shared the acting Chief Executive role from November 2018 until February 2019 when Christine Stevenson, formerly Deputy Chief Executive at Corrections and newly appointed Comptroller of Customs and Chief Executive New Zealand Customs Service, was seconded back to lead the department from February to December 2019. Jeremy Lightfoot was again Acting Chief Executive from December 2019 to February 2020 when he was permanently appointed as Chief Executive in February 2020. Mental health and substance abuse in prison populations The New Zealand prison population experience higher mental health and substance abuse issues than the general population. For example, in 2015, about 90% of prisoners had been diagnosed with a mental health or substance abuse disorder during their lifetime. Female prisoners were more likely to be diagnosed with a mental health or substance abuse disorder than their male counterparts. All prisoners were three times more likely to