Five police officers have been put under investigation over their response to the disappearance of former Folkestone teen Jayden Parkinson from Oxford in December last year.
The 17-year-old's boyfriend Ben Blakeley was jailed for life with a minimum 20 year term for her murder last week.
The Independent Police Complaints Commission launched its investigation in March and has taken several statements and gathered evidence.
Teenager Jayden Parkinson used to live in Tennyson Place in Folkestone
The enquiries revolve around Thames Valley Police's contact with Jayden, Blakeley and alleged threats Blakely made to Jayden and members of her family before she died.
Today, they published an update on the findings of the investigation.
The police watchdog has served the officers with misconduct notices, and is examining why she wasn't initially classed as high risk.
Jayden's body was found in a disturbed grave in Didcot, Oxfordshire, just before Christmas last year after she was reported missing on December 4.
Investigators are examining what actions were taken in response to the report between December 4 and 12 and confirmed that officers classified her to be at "medium risk" during the first few days of her disappearance before being "reclassified as high risk on December 10", a statement from the watchdog said.
It added that the police investigation was then transferred to the Major Crime Team on December 12, the day Blakeley was arrested on suspicion of her murder.
Ben Blakeley was sent to prison for life last week for murdering former Folkestone girl Jayden Parkinson
The IPCC is now establishing whether the risk assessments were appropriate and exactly what information was gathered about Jayden and Blakeley.
IPCC's associate commissioner Guido Liguori said: "Jayden’s family continue to go through an incredibly difficult time, and I again offer my condolences to them.
"Now that the murder trial has concluded, we can provide a clearer picture of our investigation and the progress that has been made in recent months in parallel with Thames Valley Police’s criminal investigation.
"As well as examining the individual actions of officers and staff in response to Jayden being reporting missing and whether these were appropriate, our investigation has also been looking at the force’s policies and systems around missing person reports.
Flowers placed at the grave of Jayden Parkinson at St Martin's Church in Cheriton
"There is still work to do and it is vital that we establish as full a picture as we can as to how the force responded to Jayden being reported missing, and the contact officers and staff had with her and Ben Blakeley in the months before her murder.”
Jayden and her family used to live in Tennyson Place in Folkestone before moving to Oxfordshire.
She was laid to rest in St Martin's Church in Horn Street, Cheriton, in February.
Full findings from the investigation are due next year.