This is part of the problem here. The official police statement is that everything was secure AND no signs of forced entry were evident.
Which is already saying too much and compromises the investigation.
Your response seems to intimate that this may indeed be the case. If so, it would be prudent for the COP and the officer to state that a family member/friend/acquaintance/whatever had legitimate access to the premises and may have taken the firearm without permission.
One of the best investigative tools you have is when the suspect feels comfortable. Stating publicly who the suspects are is never smart. The family member may not be the one who went into the house but simply provided the appropriate intel. This scenario still leaves a suspect who is not the family member and is not the person who was charged with receiving the gun.
Follow...
Many investigations are solved with the help of intel gathered on the streets from either informants and/or people who hear things while seated in restaurants, bars etc.... the motivation for these people to pass this info to the police is varied. Some do it out of greed (because they get paid for it) others do it out of revenge, others do it because they feel it is the right thing to do. Sometimes it is important to know what the motivation is. The hard part is attempting to figure out how these people learn the information that they are giving and if it is factual and/or accurate. This is sometimes difficult. By giving out aspects of the incident/investigation in the press you do not know whether someone is speaking from actual knowledge of the incident or of what they read in the paper or heard in the media. This can lead to false leads and hundreds of manhours spent looking in the wrong direction.
A proper police investigation is about solving the crime swiftly and professionally. Not satisfying the curiosity of an internet forum.