The instrument-rated pilot was conducting a personal, cross-country, visual-flight-rules (VFR) flight and there was no record of the pilot having a formal weather briefing before departing. Automatic Dependent Surveillance – Broadcast (ADS-B) data and data recovered from the airplane’s multi-function display (MFD) showed that, after departure, the airplane proceeded direct toward its destination on a southerly heading and climbed to an altitude of about 1,100 ft mean sea level (msl). About 13 minutes later, the data showed that the airplane had turned to an easterly heading and then back to a southerly heading as it descended to about 900 ft msl. The data then showed the airplane turning back to the west as it climbed to about 1,460 ft msl. The last recorded data point indicated that the airplane was about 1,363 ft msl located about 930 ft northeast of the accident site. The airplane impacted wooded terrain about 1,286 ft msl and came to rest upright. The wreckage debris path was about 300 ft in length. The impact signatures observed on the trees and wreckage indicated that the airplane impacted trees and terrain in a slightly nose-low attitude.A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Recorded engine operating data from the MFD showed that during the last 36 seconds of recorded data, the engine was operating at 2,680 rpm and 25.8 inches of manifold pressure. Recorded weather at the departure airport showed that VFR conditions existed at the time the airplane departed. However, VFR to marginal visual flight rules (MVFR) conditions existed throughout the area, with an area of instrument flight rules (IFR) conditions near the accident site, which included an overcast cloud layer at 900 ft msl. Law enforcement reported that when Page 2 of 12 WPR22FA298they arrived at the accident site, they observed a fog bank about 700 ft above the ground and about ¼ mile north of the accident site. A pre-purchase report supplied by a maintenance facility about 2 years before the accident stated in part that “PFD [primary flight display] & MFD Screens showing signs of possible failures.” Another maintenance facility reported that about a month before the accident, the pilot/owner had brought the airplane to their facility for issues involving the PFD and MFD. The representative stated that neither display was working, and that the PFD had a magenta backdrop that indicated “an internal power fail” and the MFD was operative, but the back lighting of the display was not functioning, which made it “virtually impossible to see.” Neither the engine or propeller logbook contained entries pertaining to the repair or replacement of the PFD or MFD, thus it’s likely that neither display was replaced or repaired prior to the accident flight.  It’s likely that while en route, the pilot encountered an area of deteriorating instrument meteorological weather conditions (IMC) that obscured terrain and reduced visibility, and as the pilot attempted to turn around and exit the deteriorating weather conditions, the airplane struck trees and the terrain. It’s also likely that the pilot was operating the airplane with known mechanical issues with both the PFD and MFD, which would decrease the pilot’s ability to maintain situational awareness.  The pilot's autopsy identified dilated cardiomyopathy, which could result in a sudden impairing or incapacitating cardiac arrhythmia. However, based on ADS-B data and physical evidence, a sudden incapacitating medical event is unlikely to have occurred. The pilot had a history of high blood sugar, and his postmortem urine glucose was consistent with high blood sugar. The absence of detected glucose in his vitreous fluid indicates it is unlikely he was experiencing any severe metabolic disturbance related to high blood sugar at the time of the crash. Both cardiomyopathy and diabetes/prediabetes may be associated with fatigue, but whether such effects were significant for the pilot is unknown.The pilot's toxicology testing indicated that he had used doxepin. The measured levels of doxepin and nordoxepin in heart blood indicate a possibility that he may have been experiencing sedating effects from the medication, but no more-specific conclusion can be drawn, particularly after accounting for the possibility of postmortem redistribution. Whether impairing effects of the pilot's medical conditions or use of medications contributed to the accident could not be determined.