To accompany their appeals , Met Police has been releasing CCTV footage to encourage anyone who recognises those involved to come forward and help with the investigations.
Here we look at some of the most recent CCTV police appeals on some unsolved crimes.
Putney jogger appeal
Police are investigating an incident where a man appeared to push a woman into the path of a bus.
At about 7.40am on Friday (May 5), a 33-year-old woman was walking across Putney Bridge on the east side heading towards Putney Bridge tube station when a male jogger pushed her.
He knocked her into the road and into the path of an oncoming bus, which narrowly missed her.
The bus stopped and passengers got off and rushed to the victim, who suffered minor injuries.
About 15 minutes later the jogger came back the other way across the bridge and, when the victim tried to speak to him, he did not acknowledge her and carried on jogging.
The jogger is described as a white man, aged in his early to mid-30s, with brown eyes and short brown hair.
He was wearing a light grey T-shirt and dark blue shorts.
Anyone with information should call Putney safer neighbourhood team on 020 8785 8874.
Knifepoint robbery in Chelsea
At around 3.30pm, a 31-year-old woman and a 31-year-old man were approached by two men on a moped in Sprimont Place, Chelsea.
The suspects threatened the victims with a knife and demanded they hand over their watches.
One of the suspects pointed the knife towards the baby in the pram that the couple was pushing.
After the couple handed over their watches, the suspects made off towards Elystan Place.
None of the victims were injured.
Both suspects were wearing black crash helmets and are described as being white men wearing navy blue tracksuits and black Nike trainers.
If you have any information about the incident, call Kensington and Chelsea Police on 101.
Knightsbridge moped attack
On Monday (July 31), a pedestrian was rushed to hospital after having liquid thrown in his face by men on a moped.
The attack took place at 8.33pm in Walton Place, near the world-famous Harrods.
The 47-year-old victim was treated by London Ambulance Service before being taken to hospital.
He was treated for minor injuries and subsequently discharged from hospital.
It is believed the liquid was thrown at the victim during an attempted robbery in Walton Street at the junction with Pont Street.
Footage has been released which captured the suspects shortly after the incident, showing them dressed in dark clothing and wearing helmets.
Witnesses to the incident in Knightsbridge have been urged to contact police by calling 101.
Moped attack in Lewisham
Shocking CCTV footage shows the moment a woman is dragged to the floor during a robbery by moped drivers in Lewisham.
A man wearing a helmet is seen slamming the woman to the floor, wrestling with her, before stealing a gold necklace.
Met Police was called at 4.40pm on Tuesday (June 20) to Clarenden Rise in Lewisham, after the 52-year-old was approached outside a Hindu temple by a man wearing a crash helmet.
The suspect grabbed the victim's £600 gold necklace and tried to remove it from her neck.
The victim resisted and was dragged to the floor before the necklace broke.
The suspect got onto the back of one of two mopeds at the scene before two men drove off with the assailant as a pillion passenger on one of the mopeds.
The first suspect was described as wearing a black crash helmet, white shirt, a dark blue jacket with grey trousers and black shoes while the second suspect was wearing a black crash helmet, blue shoes and a grey tracksuit with white stripes.
The third suspect wore a black crash helmet, a grey hooded top, dark trousers and white trainers.
Anyone with information can call Lewisham CID via 101.
Keep up to date with the latest news in west London via the free getwestlondon app.
You can set up your app to see all the latest news and events from your area, plus receive push notifications for breaking news.