The Metropolitan Police were forced to admit in court that "mistakes were made" in their investigation into the attempted murder of Kate Sheedy.
Detectives failed to properly examine CCTV footage taken near where Ms Sheedy was attacked, the Old Bailey heard.
Four officers were reprimanded after a review by the Independent Police Complaints Commission.
Levi Bellfield, 39, from west London, was found guilty of Ms Sheedy's attempted murder and two other murders.
Ms Sheedy, now 21, was 18 when she was targeted by Bellfield in 2004.
She was walking home after celebrating her last day at Gumley House Convent School in Isleworth when Bellfield ran over her in his white van.
She was left with a punctured lung, her liver was crushed and her back was torn open.
The original police investigation examined security footage taken from a nearby pub.
Although six tapes were seized, only three were examined by an officer on the case.
The footage showing a white vehicle following the bus Ms Sheedy was on was not examined and was only seen when a review of the case was carried out some time later.
Two detectives were given "words of advice". A further two were given formal written warnings.
"We recognise mistakes were made in the original investigation into the attempted murder of Kate Sheedy, and measures to prevent a repetition have since been implemented at Hounslow," said a spokesman for the Met Police.
These include establishing a Public Protection Focus Desk made up of a detective sergeant, a field intelligence officer, a researcher and an analyst responsible for:
- Supporting major investigations into sexual and violent crime
- Identifying links between public protection crime (rape, GBH, domestic violence)
- Investigating intelligence yet to reach the stage of a criminal allegation (e.g. man acting suspiciously near a school)