The mother of Kadar Hussein, who was murdered in Penge a year ago, says she is "angry and depressed" she is no closer to getting justice for her son.
Mr Hussein was shot in the head in the car park on the corner of Kenilworth Road and Westbury Road on the evening of May 8 last year.
The 19-year-old, of Upper Elmers End Road, was taken to King's College Hospital but died 12 hours later.
Trai Williamson, also 19, was cleared of his murder at the Old Bailey on March 27.
Mother Muna Yusuf, 46, who criticised police after they took more than three months to arrest Williamson - at the time their key suspect, has spoken out about the situation.
She said: "At the moment it is distressing really. I haven't got any justice for Kadar.
"It makes me angry and depressed.
"The police have not handled the case well. I think if they had done their jobs properly Kadar's killer would be in prison.
She has pleaded for more people to come forward with information, saying the murder happened in broad daylight in a residential area.
She said: "I need more people to come forward. It was a warm, sunny day.
"People were around - there were people playing football in the park nearby.
"I appeal to people in Penge, whoever was there, whoever saw anything, needs to come forward and put things right.
"Imagine if it happened to your children or brother or sister.
"Sometimes people don't want to talk, but the one piece of information they give us could make the difference."
Talking of how she is coping with life without her son, who she last spoke to just an hour before his death, she said: "I cry and cry every day but it isn't going to bring him back.
"I cannot describe, words cannot express how I feel.
"You have got a hole in your body. It is never healing."
A police spokesman said: "The murder investigation remains open and the MPS remains committed to identifying the person or persons responsible for killing Kadar Hussein."