It has been confirmed that at approximately 07:45 local time, in the Robinson family home, Mr Robinson's LEGO Detector recorded a confirmed 'event' upon the stairs.
The LEGO Detector, one of a pair operated by Mr Robinson, consists of two complex 'lengths' of calcium-based microstructures, carefully engineered to support Mr Robinson's perambulatory activities, at a basic right-angle to each other. There is a mostly vertical length primarily calibrated to resist the force of Earth gravity and a mostly horizontal one that is used to maintain the overall verticality of the former, whilst in operation. For operational reasons, including the need to dampen unwanted external forces, they do not consist of single elements, but are actually a collection of loose-linked structures, surrounded by a supporting sheathe of padding, sensory networks and maintenance tubes through which a basic combined heat-exchange, oxygenation and fuel-bearing liquid flows.
The above device is often deliberately desensitised by successive layers of fabric and harder materials, especially when used in conjunction with experiments in propulsion towards both monetary gain, via employment, and monetary loss, in the form of retail, these traditionally taking place outside the Robinson family home where environmental conditions are often detrimental to the apparatus being undampened and unprotected. (Those familiar with the Robinson Family Home may be aware of some other attempts at both forms of monetary flow using the family computer, but neither has yet been deemed completely satisfactory without supplemental external efforts.) This event, however, occurred during a short period of time in which the relevant steering group had not yet anticipated the need for changing the mode of operation from the basic unclad format.
The actual detection was heralded by a spike in the background detection data by the lower beam of the detector, and was indicated by a loud audio signal once the detection had been sufficiently processed by the Master Control Room for the device. Full confirmation of the event was delayed by a short period of necessary down-time by the LEGO Detector concerned, the paired Detector doing double duty for the duration whilst the full extent of the original detection was fully investigated and the original Detector inspected for damage. (In the immediate aftermath, a pattern of two by eight 'dots' were observed to have been impressed upon the Detector's lower surface, but later observations by Mrs Robinson affirmed that these were only temporary and could now hardly be observed at all.)
Further calculations and investigations are needed, but it is highly expected that once the scientific community has collated the evidence and examined the physical evidence, including that which can be observed in situ upon the stairs, that the source of the detection may well have been one or other of Holly Robinson (5) or Ben Robinson (7), normally located at that time in one of the smaller upstairs bedrooms. Both bedrooms are known to contain large LEGO clusters (themselves rarely triggering a similar LEGO Detection event, due to their larger mass, visibility and stability), from which single LEGO particles have been known to escape during high-energy events, especially in the early night-time hours when local activity is supposed to be reduced. It is supposed that the LEGO particle itself had managed to remain undetected overnight whilst the LEGO Detectors and their connected infrastructure were themselves taken down for their regular overnight maintenance and cool-down.
Mrs Robinson later opined that, whilst there was much excitement at the time, whichever of either Holly Robinson or Ben Robinson that it was who actually precipitated the episode were lucky that nothing as substantial as a full system crash had occurred, with Mr Robinson, and that next time such particles might irrevocably end up lost in the the space of vacuum. Mr Robinson has not yet revealed much more about the detection, beyond the burst of four-letter data automatically given out during the initial announcement.