Possibly.
If she was pushed sufficiently violently, there may be palm shaped bruise marks on her back or grasp marks on her arms.
I imagine, too, a lot would depend on the woman. If she is younger, in good health, not a drug or alcohol abuser, not suffering from any conditions that may have dizziness/vertigo/lightheadedness as a symptom, not taking any meds that might have those as side-effects, they might be more inclined to suspect foul play. If she's the opposite, they may dismiss it as an accident.
If the investigating officers know the victim and know she's in good health and so on, or if a neighbor/friend/relative can convince them she would never fall down the stairs, they may push the crime lab techs or ME to dig deeper for evidence of what really happened.
Long answer to a short question, but I hope it helps.
Dave