"All lines of inquiry were considered in the early stages of the investigation. The investigation was detailed and complex and officers had a duty to explore every avenue of inquiry and retain an open mind about the circumstances.
"They carried out numerous actions including door-to-door inquiries, leaflet drops, searches, interviews and forensic analyses.
"The CCTV evidence took some time to collate and analyse but then clearly showed a veiled suspect trailing the victim before the attack.
"Konye was arrested as the investigation progressed."
Two people have been arrested after a 21 year-old woman had acid thrown in her face leaving her with severe burns. Naomi Oni was attacked in Dagenham in December.
Another 21 year-old woman was arrested on Friday and a 28 year-old man was arrested yesterday. Both have now been released on bail. Anyone with information can call Barking and Dagenham police on 020 3276 1056 or Crimestoppers anonymously on 0800 555 111.