The man, aged in his 60s, was found in an alleyway at Langhedge Lane, N18 at around 3am on Thursday, 2 September. He was suffering a serious leg injury and has been taken to hospital for treatment. He remains there in a critical condition.
His next of kin have been informed.
Officers are keen to speak to anyone who was in the area around Langhedge Lane and Bridport Road from around 02:30hrs and who may have seen how this man came to sustain his injury.
If you can help, please call 101 or tweet @MetCC and quote CAD1301/2Sep.