“He has a partner, Aisha. Was she the one I felt watching? Did something go wrong between them and did they have a fight?”
John Jacks Jones was beaten to death in the alley where Lane went and she felt someone watching her and she thought it could have been his partner Aisha who watched her and kill Jacks.
The death of Jacks had created suspicion for Lane. If Jacks didn’t die Lane wouldn’t be following Aisha and extend the story. Since this happening Lane get caught stalking her which builds tension and action.