An air carrier Mechanic did not properly release an aircraft for flight following maintenance before flight.

Narrative

I was called to line to inspect work packages. The only crew chief at the line was not qualified. A mechanic; who was qualified; was stepped up to Crew Chief to do the package. Found out after getting package that the mechanic was not release qualified and that there was no one at the line who was. In starting the package the Supervisor called out that they needed the log book (the inspections department in recent times has been listed as the reason for delays when it comes to paperwork and have had to explain themselves for it). Due to this; so I or inspections would not be blamed for the delay; the package and book were rushed. I performed the review while standing at the copier in the Line Crew Chiefs office. Two mornings later I received phone call from Line Supervisor about a missed release. Maintenance needs to have properly trained and authorized crew chiefs. Packages are being dropped on the crew chiefs close to gate time causing them and Inspections to rush to make gate. All this puts undo pressure and stress on the crew chiefs and inspectors. Have enough mechanics and crew chiefs to handle work load (that night only 1 crew chief available and was not properly trained or authorized to handle the work load). Get proper training and authorization for the crew chiefs. Have enough staff available to handle workload. Don't put undo pressure and stress on staff. Don't rush reviews. Take the delays.