In Dead On Arrival, you have to consider every possibility. Using the inspection view mechanic, you can examine windows and doors for signs of forced entry, be it broken glass, damaged framing, or locks that have been tampered with.
Forced entry can reveal multiple key pieces of evidence in an investigation, so make sure you dust door handles for fingerprints, photograph all damage and points of impact, and measure and cast shoe impressions from the entry point and surrounding areas.
Every bit of evidence you find uncovers another piece of the puzzle, and it's your job to put it all together!