Chief Constable Collins has been a police officer for 32 years and was appointed to her latest role on a temporary basis in June 2014 before being promoted permanently in November 2016.
She joined West Yorkshire Police in January 2014 as the Deputy Chief Constable having served for over six years as an Assistant Chief Constable in Derbyshire Constabulary.
In her post she has overseen high profile investigations such as the tragic murder of MP Jo Cox and the M62 shooting of Yassar Yaqub.
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Her statement reads: "In July I would have completed 32 years’ service in policing, 12 years of those as a chief officer in Derbyshire Constabulary and West Yorkshire Police.
"Following my recent secondment to the College of Policing where I have had the privilege to successfully lead the national strategic command course, I have decided that it is the right time for both me and the force that I retire.
"I will always love policing and it has been an honour to serve our communities, most recently as Chief Constable of West Yorkshire Police.
"I believe that West Yorkshire Police is an excellent force and I am incredibly grateful to have had the opportunity to lead the dedicated officers, staff and volunteers who work for us and the support I have generously been given by the public and the Police and Crime Commissioner.
"I recognise that my announcement means that I will be leaving shortly, however, I am stepping down for personal reasons to face some new health challenges that I would prefer to manage in private rather than as Chief Constable in full public view.
"For this reason, I will be stepping down from the service at the end of April, leaving a very capable and talented team to continue to lead the force.
"I have very mixed emotions about retiring as I have loved my job, loved serving our communities and loved working with so many fantastic people.
"I have tried to encourage an understanding of the very human aspects of policing, with a culture that truly cares about our communities, given the very real challenges that all of the public sector are facing at the moment."
Mark Burns-Williamson, Police and Crime Commissioner (PCC) for West Yorkshire, added: “I would firstly like to personally thank Dee for her continued dedication and hard work in often very challenging times.
"Her leadership through a sustained period of austerity has ensured a strong position for her successor and for the people of West Yorkshire.
“Dee has overseen some of the biggest events in the country and the most complicated investigations, often receiving international attention.
"Her contribution to policing in West Yorkshire has been exemplary, not to mention her impact on the wider service.
"In particular, her dedication to championing opportunities for women and leaders, which is testament to her character and will be part of her on-going legacy.
"I completely understand Dee’s reasons for retiring and wish her all the very best for the future.
“I am confident in the very capable chief officer team, which we currently have in place and look forward to building on Dee’s success with the exciting opportunity to recruit the next Chief Constable of West Yorkshire Police.”
Chief Constable Collins is the NPCC Gender lead and President of the British Association of Women in Policing, she leads on the National Police Aviation Service as well as being the Regional Chief Constable lead for Counter Terrorism, Organised Crime, Collaboration and sits on a number of NPCC committees and working groups.
In 2013 she was awarded the Queen’s Police Medal and in 2018 she was awarded a CBE for her services to policing and women in policing.