A disciplinary hearing at the West Midlands Police and Crime Commissioner's office ruled Yvonne Mosquito had acted unprofessionally by requesting to pray with the family of teenager Kenich Phillips during a visit to their home.
The 18-year-old was shot dead as he sat in a black car on St Marks Crescent in the Ladywood area of Birmingham shortly before 7pm on Thursday 17th March.
Yvonne Mosquito was suspended by the Office of the Police and Crime Commissioner for the West Midlands pending an investigation by an independent disciplinary panel.
It has now emerged she left the Office on Wednesday, as her contract came to an end.
West Midlands Police and Crime Commissioner David Jamieson said: "The Panel found that the Deputy Commissioner did not make the Force or the Office aware of the visit before or after it was made.
"The work of the Office of the Police and Crime Commissioner must not interfere with the operational independence of policing.
"The panel found that the actions of the Deputy Commissioner clearly interfered with operational policing."
Yvonne Mosquito's union has said it strongly deplores the disciplinary hearing going ahead while her union representative was on holiday, meaning neither the representative or Yvonne could attend.
Unite regional officer Brian Rickers said: "Unite notified the Office of the PCC last week that Caren Evans, the Unite regional officer representing Yvonne, and who has detailed knowledge of this case, was on holiday abroad this week.
"We offered a number of alternative dates for when Caren was back at work but all these were declined.
"It is Yvonne Mosquito's right under s.10 of the Employment Relations Act 1999 to have the union representative of her choice to accompany her to a disciplinary meeting."
West Midlands PCC, David Jamieson, said: "The Panel found that, based on evidence submitted by both Kenichi Phillips' family and the Force, the visit caused ongoing upset and distress to the family and, at the time, damaged the relationship between the family and West Midlands Police in the middle of a complex and sensitive murder investigation.
"The family confirmed that they were made to feel that the Deputy Commissioner was in their home in an official capacity as she left her Office of the Police and Crime Commissioner business card with them, and sought to raise a range of issues that were not pastoral or spiritual.
"The family also confirmed that, despite being requested by the Deputy Commissioner to do so, they did not pray with her.
"On the basis of the Panel's findings, I have issued the Deputy Commissioner with a final written warning and asked her to apologise, in writing, both to the Force and the family.
"She has so far not done so."
Premier's Alex Williams joined Antony Bushfield on the News Hour programme with details about the case and you can listen by clicking here: